You could most likely sell your lyrics online for a pittance or run the risk of copyright problems if posted unprotected.
If you are a credable songwriter and would like to pursue that route then go to a publisher (or create the interest) and do it properly.
If just for fun and to see what happens, by all means go ahead. I know there are places on the net that cover these issues but I don't have any links off the top of my head.
