A stupid question but..

Could you help me make a normal picture into icon size?






Okay, I'm a TAD new at this icon stuff. But I do use Photoshop 7.0. I flipped threw some of the pages, and didn't seem to find this question, so please don't get angry if it's already here!

My question is the simple fact that..I can't seem to get my picture into perfect icon size...

I try cropping it, but it mearly takes me forever to get it! And once I do, it's to small, and the iamge isn't the way I want it to be.
So if you could..could you please step me threw with something to help me get a normal sized picture/vector/banner/whatever into a 100x100 size? I would much apperciate it! <3