Not a problem.
If you're using a Windows OS, hold down the <SHIFT> key and press the <PrtScrn> key. This will save a copy of the screen, much like 'cut and paste'... but different.
Open 'Paint' by clicking on 'Start', 'Programs', 'Accessories, 'Paint'.
Once Paint opens, do a <CTRL> V to paste the screen save.
Answer yes to enlarge the bitmap.
Do a 'File', 'Save As' to save the image to your machine.
You should then be able to upload the image.
Note that this works on Win7 and down. If you have something newer, I can't help as I don't use Win 8.x or 10, but I'm sure someone can.
