How do I create a second user on my MacBook pro?

I am a new user to the Mac family, and I'm loving it! I bought my MacBook Pro 15" with retina display with the intention of me being its only user. I am now reluctantly thinking of letting my almost 15 year old daughter use it. She has used it as a "Guest User", but upon logging off, all of her information gets erased. How do I create a second user? I want to make sure she cannot access my files, alter my settings, etc. But I want her to be able to save whatever she is working on. And I also want to be able to access her user to monitor her internet usage, and also add parental controls. Mahalo folks!