How can I lighten a dark photo?

If you are using a newer computer, with windows vista or 7 (which most people are), you can use windows live photo gallery, which should be the default program used for opening JPEG's. It has a feature called "Fix", which you can use to adjust exposure, color, cropping, etc. That's the easiest method for simple editing. I've got 3 versions of photoshop on my laptop, but when I want to just lighten a photo, I use windows live photo gallery. The win7 version even has a histogram with a levels profile. You will see the Fix menu above the image when you open it. Click it, then select "Exposure", move the brightness slider to your taste. Close the image and it will non-destructively save the file (meaning, you will be able to undo any changes you make).

Any basic photo editor like gimp can do that.

There are many ways to bring out the dark spots.

I would try decreasing contrast first. If that doesn't work, boost the brightness.

You can do it on Photoshop.

But if you don't have photoshop you can do it on a program online called picnik..

http://www.picnik.com/

just upload your photograph go to lighten :)

You can do it on Microsoft Word.