The screen has two parts, the panel of controls and the picture of the part: on a wide screen they stand side by side with the panel down the left, and on a narrow one the panel is on top with the picture below it. The sentence at the top of the panel says what the app makes, and the link under it is the one that brought you here.
The steps, in the order you do them. Each one is a control on the panel, top to bottom, except where this page says otherwise.
Start by bringing in the part. The control at the top of the panel takes a job and the drawing it names, picked together, or a drawing on its own. If you have neither, the chooser under it opens one of the parts this build ships, and the line under that lists the file types it accepts. A drawing that does not say which of its layers bounds the part is asked: a control appears offering the layers it holds, and choosing one writes the job that layer makes and reports what it still needs, because a fresh drawing states no side for its operations to cut on. Once the part is in, its size is shown, so you can check it against the drawing you were given before you cut anything, along with the name of the job's own file, the name of the drawing it was made from, and anything the reader had to say about reading it. A part that came from the chooser also names itself in a panel further down.
The Stock group is the plate you are cutting from: its origin, its width and depth, and how thick it is. The part zero, the corner the machine measures everything from, is not in that group. It is in the Job group, the next box down, with the height the tool retracts to between cuts and the units the whole job is written in, because those are what the job document says about the setup rather than about the plate. The units are yours to choose: pick the other one and every measurement is restated from the same part, which does not move. Further down again, past the group holding the cutter and the numbers of the cut, the Heights group holds the height the tool clears the work at and the top of the material, and works out the distance between them for you. Every length is in the unit the job document declares, shown beside it and read off the job itself; the feeds carry their own rate and the spindle speed its own turns. All of it is drawn as you type, so the blank and the zero mark you see are the ones the job will use.
Pick a cutter from the library in the group below the Job panel, or type a diameter of your own there. The Job panel above it holds the rest of the cutter: tool shape, which is what the end of it is, and flute length, both yours to change, and the diameter you typed, shown there as a readout, which is why that one cannot be typed into. The material rows are in that same Job panel, under the cutter: say what the plate is made of there. The feed, the plunge rate and the spindle speed fill in from a published table for that material and that size of cutter, and if the row the table answered with is far from your cutter, a note under them says which row it read. Every one of them stays editable: if your machine wants different numbers, type them and yours are what the job carries.
An operation is one strategy over one region of the part: the strategy is the pattern the cutter follows, the region is what it clears. It is not one pass. A pass is the cutting the tool does between plunging in and lifting out again, and one operation takes as many of them as the shape and the depth need. The passes row in the summary counts them, and because every pass ends in one lift, the retracts row further down counts the same thing. Choosing the operation is choosing a name rather than filling in a form: pocket clears the material inside a boundary, parallel sweeps the region in straight stripes. The numbers come afterwards.
The stepover is how far the cutter moves sideways between passes, and the max step down is how much it takes off in one go. Both start from the tool and the material you chose and both are yours to change. The level each operation cuts down to is the floor on that operation's own row, because a job with two pockets at two depths is an ordinary job and one number cannot say both. A button under the rows adds an operation, and each row carries its own controls to delete it or move it. The engine cuts by depth whatever order the list is in, so moving a row changes the order only among operations that share a floor, and the up and down buttons on a row go dead where they cannot help, each with its own reason on it.
The button below the groups, which reads calculate & simulate, plans the job and hands back the path the cutter will follow. Change a number and press it again: everything else you set up stays as you left it, and only what you changed moves. A line under the button says how the job came out, and if the job was refused instead, a box under that names the stage that refused it and what it objected to. Where the page works the job out on this computer rather than in the cloud, a line under the button names each step as it runs and how long it took, with a stop button that ends the run and leaves everything else as it was.
Orbit and zoom the picture with the mouse, or with one finger to orbit and two to zoom. A bar of buttons lies over the picture along its top edge: the first group turns the camera to a named side or to the iso view, which looks at the front from above; the second turns one layer on and off at a time, each button reading its layer's own name. Stock is the plate you started from, setup the part zero and the height the tool clears at, part the shape the job asks for, toolpath the moves, tool the cutter itself, and uncut and gouge are the two the simulation adds: what the program did not reach, and where it went into the part. Toolpath holds the cuts and the moves between them together, so it goes away as one; the others come off on their own, which is how you look at stock without part inside it. A ruler in the top left of the picture, clear of that bar at either width, says how wide one square of the grid under the part is, so you can judge a size off the picture. Under the layer buttons, a legend names every colour the picture is drawn in, one line each with a swatch of the colour and what it marks, and it lists only the colours the picture on the screen uses; a layer button hides every colour of its layer at once, so a colour you cannot place is read off the legend rather than found by turning layers off.
The same run takes the material off in the order the machine would, so what you are looking at is the plate as it will actually be after the program has run. A second bar lies over the picture along its bottom edge and walks the cut, each button reading what it does: start puts the plate back as it came, back and step move one move at a time, play runs the whole cut through, end goes straight to the finished part, and the slider beside them scrubs to any point in between. Material the cutter could not reach is shown where it is left, and anywhere the tool went into the part when it should not have is flagged in the picture and marked on the slider rather than left for you to find.
Back on the panel, beneath the button, the run reports, one row each and under these names, in this order: strategy, the operation it cut with, under the word you chose it by; passes, how many the program takes; cutting, the number of segments and the distance they add up to; air, the distance travelled between them; retracts, how many times the tool comes out; peak engagement, how much of the cutter was buried at its deepest, entering and then steady; estimated time, how long the cutting itself should take; gouge area, how much was cut away that should not have been; and uncut area, how much the program did not clear, with the part of that another tool could still reach and the part nothing can. Two more rows appear only when there is something to say: offences, the checks this run failed, and gouged by, which pass and which move cut outside the part. Every number carries the word for what it is, and every length and area is in the unit the job document declares. Those are how you tell one way of cutting the same part from another. What each stage of the run itself cost is on the last line of this box, under "timings", closed until you open it: it says how the engine spent its time, not how the machine will spend yours.
The last step of any job is taking the G-code away. The run has already written it, for the controller this build posts for, and the box under the run's numbers, labelled post, names that controller rather than choosing it: the program is written by the run, before the box can be touched. Below it, a link reading export G-code downloads what was written, under the name of the job you opened, and under that a second, export job.toml, saves the job itself as a job file, which is what the command line reads to run this job again. If a run produced no program, the download link is withdrawn and a line says so where the link was.
At the very foot of the panel sits a closed line reading "About this build". It opens to say which build of the service you are looking at and what a browser has to offer to run it. Nothing under it changes a job, and nothing on it needs reading to cut a part.