Is this picture fixable with some sort of programming?

My brother had asked me to take a picture of him skating. I used my new Casio Exilim camera with the high speed video and the forty shots setting. I decided to use the forty shots one but then realized it got extremely dark. I got the pictures perfectly but it is just so dark. I tried to brighten it on my computer but then it got gray and very fuzzy. Any ideas? Also, for future reference, how do I get it so that it doesn't go completely dark? I'm not very intelligent when it comes to cameras, that's why I was so confused as to why my mom got it for me, but I am trying my best to learn. Thanks 8)