first off, your'e going to have to resize a picture to at least 72 KB and be 100 width x 150 height pixels. If you need help doing that, just ask and I'll do it for you.....anyway, You need to go to 'your profile' up by board settings, etc. then click on "update profile" and "add Image" when you're on your profile updating page. click browse, select the file you want to use, and click okay...click upload, and it should work!!
hope that helps!!