Newb question-sit activate

I want a sound to play when someone sits on an object. I have PlaySound all set to go, and it works when I touch the object. How do I make it happen upon sitting?

From: http://secondlife.com/badgeo/wakka.php?wakka=llAvatarOnSitTarget

default {
    state_entry() {
        llSitTarget(<0.0, 0.0, 0.1>, ZERO_ROTATION); // needed for llAvatarOnSitTarget to work
        // Note that if both the vector and the rotation are zero,
        // the SitTarget is removed instead of set and the following will not work:
    }
    
    changed(integer change) { // something changed
        if (change & CHANGED_LINK) { // and it was a link change
            llSleep(0.5); // llUnSit works better with this delay
            if (llAvatarOnSitTarget() != NULL_KEY) { // somebody is sitting on me
                llSay(0, "Get off!");
                llUnSit(llAvatarOnSitTarget()); // unsit him
            }
        }
    }
}

and instead of the llUnSit... you replace it with your llPlaySound. Also you can remove the llSleep which isn't needed, nor the llSay (except perhaps for debugging).

Thanks a bunch