First off bro, congratulations. Second, start slow. It's the initial penetration that they usually find painful. After your in you should be able to pound away without hurting her and definitely balls deep. If you don't get to stuff your whole dick in her it's not worth doing. Third, ace the condom. Fuck safe sex! If you hit the puss bare then hit the ass bare as well. Feels much better for you and for her.