Sorry you’re so frustrated. For a short term fix I can attach a square cut line that might work for you. You can save it and then load it into the GUI. The thing is you are going to have to line it up with your image that is already engraved. I would suggest bringing the square into the GUI and making it the size you need. Then tape down a piece of paper on your tray and score it with the square using the fastest speed and a power of 1. This will give you an outline of where to place you engraved piece. When everything is in place, go ahead and cut the square out.
here’s the file
In the long term, everything you need to learn how to make this on your own is in the help section 
Good luck!