Changing a high resolution image?

A while ago, I scanned in a picture, but must have scanned it at something like, 1200 dpi, cos it's about 97MB, which is obviously too big. I have the image on my computer but it is too big to scan anywhere because no host will accept it. I was wondering if there is any way I can make it any smaller (the host i'm using now accepts a maximum of 15 MB). It may seem like a stupid question but I really don't know about all this stuff, I just wanna be able to get my stuff up on the internet. Any help is appreciated, thanks.