Woah woah, slow down...! You're new to jailbreaking, so proceed with caution. You might end up with a bricked phone.
Listen. You cannot ask for jailbreaking help by simply saying "I have a 4S, how to jailbreak it?".
You need to know some things:
1. What's the iOS version you're running, and what's the version you're going to jailbreak (and whether it is jailbreakable or not).
2. What's the current status of your device (factory unlocked or software/hardware unlock). Jailbreaking might cause you to lose your unlock.
Next, just search on YouTube in the following format:
"Jailbreak *iPhone model* iOS *iOS version* "
For example, "jailbreak iPhone 4 iOS 5.0.1". Check out the top video results.
A LOT of people have very helpful videos on how to jailbreak, depending on the condition.
Please do not trust sites like jailbreakmyiphone.com or stuff like that. You have to DIY, or get someone to do it for you.