Speakers

I'm trying to hook up an amp and two subs to my 1997 Jeep Grand Cherokee Ltd. I know I need an adapter to hook up the RCA cable but I don't know where to get one or how much it'll cost. Can anyone help?

Ok...I bought a 2 Channel Line Output Converter so that I can plug the RCA cable from the CD deck to the amp. I have no idea how to hook up this converter. Can anyone help?