Notice that the lines are all green - this represents cut lines, which is what we want. Click on the Properties tab. Set the Database to FL4500 (this is our machine). Set the thickness to 1/8" (.125). Change the Y size to 1.5 (I don't know that this matters, I just like to see the square match).
Click on the job tab. You can look at the job preview by clicking the "Show Job preview" button. It isn't very exciting. It should be the same outline. When you are satisfied (and you should be very satisfied), click the Make and Save button. This will save a .fab file that you will put on USB to transfer to the laser cutter.