Sega Genesis 16-Bit connection problem?

I'm having trouble connecting my sega. I'm looking online and noticed that many mention the A/V RCA Cable, but I haven't played or set it up in a long time that I don't remember if I lost or not or if I even had it. I think I got it working without that cable before :s. If anybody know's how to set this up without the AV RCA Cable it would be helpful, Thanks!