If you're using a PC, there's a button somewhere at the top right coorner that reads "PRT SCR" or "PRT SC" or something similar.
Press that and you should see your cursor blink.
Open paint or something similar
right click --> paste
Or
edit --> paste
Resize as needed
file --> save as
If you're using a Mac,
link.
I don't use a Mac, so all the information there goes over my head.
