Custom made album art

[CloudStalker]

This is somewhat related to the QT4 interface, since I’ve never had a need for album art before. Anyway, my question is this: is it possible to convert any JPEG or PNG into a usable album art? What (free) program can I download to do this, if any?

This is simply for personal use on my computer, I just prefer a unique look for my albums and I also want to add album art to those that don’t have one. Thanks in advance for any help, it's already appreciated.

Sorry if this sounds like a newbie question, but I am new to this after all.

[3breadt]

The Album Art is stored in the ID3 Tags of your music files.
To edit them I use http://www.softpointer.com/AudioShell.htm