How to paste together screen captures

[vmxa1]

I know a number of players here are great at taking pieces and putting them in one shot.
Say a trimmed down score with the top 4 civs layed over the congrats display. What tool is needed and how is it done?
I know how to crop the screen shot with something like Hypersnap and resize it with Irfanview. I have Paintshop Pro and Dreamweaver, but I have not used them much.
I do not know how to import more than one picture into a single shot.

[Solomwi]

I'm sure you'll get MUCH better advice and methods, but I've done it before simply using MS Paint, copying the cropped area and pasting it onto the collage wherever desired. Here's a non-Civ example of the results: