Make sure you are well lubricated and stay slippery and wet.
Plenty of foreplay to relax you and get you very aroused.
Some fingering, first one finger, then two, then three to relax the pelvic floor muscles.
Get on top and control the penetration the first time. Then you can switch positions.
Open yourself up a bit with your hands so that his penis is at the entrance to your vagina and your lips are out of the way.
Take it very slowly, a little bit at a time, in a sort of rocking motion to allow him to slowly stretch his way in. It should already be very slippery deep inside from foreplay and fingering.
Try some vanilla strokes first for a bit to further relax you and allow your vagina to get used to him. Then get your freak on if you want to.
Rough sex should be a no no for quite a while until you are comfortable and do not need to take any special precautions. If not, you will bleed and the area between the vagina and anus might get injured.
If he bumps your cervix, a penis ring can keep him shallower.