hey buddy this site relies heavily on its users doing their own research, you are unlikely to find many helpful replies to this question since it is very well documented if you use the search function...or google. Or just even browse through the threads a bit. But I'll throw you a bone.
1. Download Chainfire's CFautoroot. Thanks chainfire! He conveniently includes a compatible version of odin in the zip (v3.07 if I'm not mistaken).
2. Extract the zip, and run odin.
3. Press the PDA button and select the CF-Auto-Root-jfltespr-jfltespr-sphl720.tar that was extracted from chainfire's zip.
4. Completely power off your phone. If you are unsure if it is completely off, pull the battery. Press and hold the power button and vol down until it boots into download mode. Press vol up to continue.
5. Connect your phone via usb to your computer.
6. Make sure odin recognizes your phone (one of the little boxes should read com x, where x is a number. it was com4 for me). if it doesn't you will need to install the samsung mobile phone drivers. if you plugged your phone into your computer since you've had it, you likely have these drivers installed already.
7. Press start.
8. Profit! You are now probably rooted. or your phone is bricked. ha just kidding - but please research a little next time before you ask a question
PS - this voids your warranty. also you should go click on some ads in chainfire's website.