I use a Mac and record songs with GarageBand. When I try to upload them to my profile it won't let me. I have all of them on my ITunes too, but neither work when i click on upload file and go through my files to the song in my GarageBand file or my ITunes file. Is it because they aren't in the proper format or something? If so, then how do I go about changing it so it is in the right format? I'm not sure if there is a very obvious solution, but I'm just not really computer savvy at all. Honestly I've never really uploaded anything because I've never had a Facebook or MySpace, so not even a picture or anything.
Probably the format, you can change it using the DAW (or GarageBand in this case).

Hope This Helped,