s-video can come in 2 forms.. either a small round 4 pin plug as ice described, or it could be available on the scart connector, if it's a european TV. if it's an american one, it'll be the small round one.
To check if your TV has s-video inputs, look where your input things are. If you see green plus some other colors I do believe thats s-video. If it has the red/white/yellow, thats just standard RCA inputs.