I don't have photoshop. Don't wanna get it if I don't have to; I wouldn't use it often enough.

So tell me how I can (without having to pay for a program or whatever) make the contrast on pictures darker.

Basically, decided with my boredom to change around some myspace. I wanna change the old backdrop to something new, but all the pictures I'm finding are much too bright to use. So I wanna know how I can edit the contrast on them...