Go to Rat Shack, buy a stereo headphone to RCA jack. You now have a monophonic output to feed the transmitter with. Plug the stereo end into your audio source and the RCA end into your patch cord. Plug the other end patch cord into your transmitter, switch the tx on and crank the audio, you're on the air. Nothin' to it, and no soldering.
It will cost you about two and half bucks, plus tax.
Invest in a snap-on ferrite for the patch cord while your there, if you don't have a few around the radio room. Give the patch cord about 3 turns around the core and snap it shut. It will stop rf from creeping back into your audio source.