I'm not gonna tell you to wait. You're 14, you have a willing girl, you're a force of nature man, Its going to happen. I'm also not going to instruct you how to have sex. For one it's a huge liability for me to be advising a young teen, for another the information that would be relevant is likely the same stuff you got in sex ed. I will tell you some things I learned at 15.
Protection is important, with virgins, regardless of what she thinks. The only thing I could imagine more destructive to a teenager than an unwanted pregnancy would be a flesh eating virus. Be deadly serious about protecting yourself and this girl from consequences.
"I'm ready" doesn't mean the same thing for girls as it does for boys. You were born ready for sex, girls need to process the idea of sex in a lot of stages. Go slowly, watch her for uncertainty or mixed signals, make sure if she's having second thoughts anywhere along the way that you stop for her until she's ready to go.
You would be shocked at how much information about sex you can find in your local public library. Graphic anatomical information and detailed information about technique and methodology. Books are awesome.