GIMP, the poor man's photoshop

It's a great program, it's free, runs under Windows, and it's fans claim it can do everything Adobe Photoshop can do.
Trouble is, no manual. No overview. The program has a zillion options, and it's very difficult to figure out what they do. The on-line help is full of "alpha channels" and "layers" and other strange words all of which lack a definition in ordinary English.
With all the fancy options, GIMP cannot, or I cannot figure out how to make GIMP, do a cut and paste. My needs were very simple, I wanted to print out a stone wall texture that I could use to cover up the wood basement of a HO railroad building to make the wood look like a cut stone basement. I had a snippet of stone wall and all I wanted to do was copy and paste the snippet to fill up a 8.5 * 11 piece of paper.
I finally had to use plain old Microsoft "Paint" to do the copy and paste. Fancy GIMP just would not do it.