Step 4: Measure and Cut
First set the miter saw to a 45 degree angle as you see. If you've got safety goggles, put em on, because sawdust goes in your eyes. But if you like the feeling of sawdust in your eyes, then by all means, leave them off. Now make your first test cut a couple of inches off the edge of the board, just so you can see what we're going to be dealing with.
Once you have done this, measure exactly (or as close to exact as you can get) 10" from the right edge of the blade, and mark that spot right on the miter saw. Move the board to that position, make sure it is level, pray to whatever god or gods you pray to and make the cut. You now have your first 10" piece. Next slide the board to that same exact spot, and cut again. Do this until you get to the last piece on that board. In all, you should have been able to fit nine pieces on there with a few leftover scraps, as shown.
Still have all 10 fingers? Good! Let's carry on.