How do I go about this? I know a paster and he wants the churches band to play one of my songs during services. Normally they pay a fee for the music and license from some websight. I don't remember the name of the website. Anyway I am not charging anything I just want to make sure they don't sell the song to parishioners on a cd or something and only play the song for sevices. My song is copyrighted and all that.

you just need a contract for him to sign saying exactly what you said.
 
you should also give him rights to make copies for the band/choir and for putting the words on the powerpoint.  normally those are handled through ccli for churches, but if you're letting him do it for free, just put that in the contract.

Essentially what Beagle said will work. He can use it under the license at no cost or low cost if he wants to pay and you're wanting to be paid. 
 
Make sure there's a time limit in the license and clearly state the cost to the church eve if it's free. You can renew at the end of the year or whatever term you both agree to.
 
I licensed a song to a Christian pro-life pregnancy clinic for a one year term.  It was a simple written agreement between them and me. Everything worked out fine. They never used the song in their advertisements although they had the right to do so.
 
Good luck with the song.

I appreciate the info. I know what to do now. Thanks so much.