Trying to hook up an N64 to a new TV?

A friend just gave me her old N64 so I could play Majora's Mask and I've been trying to hook it up to a relatively new TV, which worked fine with the wii, but without sound. I can't get it to register on the screen at all even though there were a lot of wires. My friend mentioned something about an adaptor and I was wondering if I need one and what it would look? Thanks I know this is a bit vague but I thought it might be worth a try