Well, as a Photoshop user, I can't say I'm that familiar with the alternatives these days.
But my only warning would be that Photoshop is a heavyweight tool for professionals or serious amateurs, and requires the investment of quite a lot of time to master. Easy, it ain't.
GIMP, superb though it is, is aimed at that general type of user (
IMHO) and while highly capable, is also not the easiest to learn to use.
So I suspect your mistake might be in the Photoshop reference, when from what you want to do, a far simpler, and easier to use, program might be a better match.
What that might be, I've no idea, I'm out of touch. I used to like ACDSee, but while it was cheap, it wasn't free. What about Picasa?