Q: i have $15 dollars on my account and i am trying to send a song that is a dollar to my friend how do i do this?

Can't use existing credit to send gifts, unfortunately.

http://support.apple.com/kb/HT2736

"Note: When purchasing an iTunes Gift, a valid credit card must be on file; you cannot purchase an iTunes Gift with store credit."

there are other ways in which you are able to give the songs to people, but i will not go into that as it is illegal.