Help with Profile

[capabmx]

Hey, I was wondering if anyone here could tell me how to make it so that when a user registers, it automatically will create a folder named [TheirUsername], Folder in their named [mp3]? Any help would be greatly appreciated . The reason I ask for this is I am adding an option to upload music to their profile, and I want the songs to be stored in their own mp3 folder, so hopefully it works, again thanks!