How do i change the ringtone on the Motorola Droid?

I just got the motorola droid today and quite frankly, the stock ringtones on it suck. i put music on the memory card, but for some reason Android 2.0 isn’t letting me change any of the sounds to one of the ones i uploaded. How do i get it to let me change it to one of my uploaded tones instead of the ones that came with the device? do i need an app or a widget?