Naldoon

I need to know how this can be done. I'm a Young Male at the age of 20, as is my Girlfriend. We both have a great relationship and I treat her well. We have been dating for some time. I'm a large guy standing 6'4" with a above average "man-hood" (but not scary-like). My Girlfriend is 5'7" and very patite and i'm double her weight. Her and I have become very interested in sex, and have tried. But we can't because she is too tight. We bought her a vibrator, and plenty of lubricant. She can't handle the pain and we stop everytime. I never force anything, but it is becomming very fustrating for both of us cause we can't. We need something to dialate her or something that might work. Whatever I do, I want it to be best for her, cause we all know pain or no pain, the guy likes it. But I am very conserned with her enjoyment as well. And I want our relationships first time to be great! This would be her first time, not mine, but i'm very respectful with her. Can any of you help?