Replying to Songs in Ski Movies

So yeah, im wondering about the issue of copyrights and such when using a song in a video that you are planning on selling. Now, im sure the RIAA or whatever the fuck they are dont care if im just giving out my movie for free...but lets say i decide to put a price on it. how do i get rights to use a specific song?
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switchskier88: ive got a pretty bad ass wedge turn
i swear to drunk im not god.