it's going to take time of course. I like the advice tooth gave. You need to get her off without any penile penetration first. If you've done this great! You could also try getting her close to the point of climax then backing off and teasing. Then get her close to climax again and reapeat. Sounds rather cruel but it can be fun and you'll be pleased by the animal instincts that appear out of her
Also try using your fingers and right as you pull your fingers out..penetrate her with your penis. For the pain..I would go with the standard missionary position or let her get on top of you that way she can control the depth and pace. It will make it easier on her and eventually you! Good luck and keep us posted
