First, open a program like Paint (in Accessories in Windows). Go to the full screen feed. Then, when you see something you want to capture in the feed, press ALT and Print Screen button at the same time (or function and Print Screen, which is how my keyboard does it.....)This action copies the image.
Then go to PAINT, and paste the image. (Control and V) Save it and there you go!
If that doesn't work for you, come back and we can work on it . . .