Please read through all of these threads that I'm going to post BEFORE doing anything so as to make sure you understand the process.
To root and understand the process: Link 1
To return to stock and relock: Link 2
One click toolkit. Use this to actually root/unlock/relock. MAKE SURE YOU READ EVERYTHING FIRST: Link 3
Here's a step-by-step video
explaining everything for you.
It might void your warranty temporarily - but you can return the thing to stock as long as you don't drop it into a bathtub, so it won't be an issue "re-warrantying" it.
Just make sure you know how to do everything manually in case something goes wrong. And don't be afraid to read a bunch before you do anything. Knowledge is key!
Make sure to hit 'THANKS' if I've helped you!