Jimmy: Basically, you either need to obtain permission from the songwriter, or obtain what is called a "mechanical license" from an agency representing them. The typical royalty rate is about 7-8 cents per song, per copy sold.

A good place to start is the Harry Fox Agency/NMPA website at http://www.nmpa.org/. There is a database of songs registered with them and downloadable (and on-line even) forms for obtaining mechanical licenses. Many well known songs can be licensed through them (the filk music club I'm involved with has used them several times), the process isn't hard.

If a song isn't in the database and you have an address for the writer, just write to them. Our experience has been that most folkies are happy to grant permission for covers (again, we've done this for several songs). -- Gary