I while ago I wrote an article for WikiHow about how to decorate picture frames with dimensional (fabric) paint. I'll link to the article rather than re-post each step-by-step photo here.
http://www.wikihow.com/Decorate-a-Picture-Frame-with-Dimensional-Fabric-Paint
You can use this method on many things besides frames. I like to decorate those inexpensive unfinished wood boxes you get at the craft store this way- they come out looking fantastic! :)
Here's a picture of a finished frame:
