My first suggestion would be to make sure that you engage in lots of foreplay to make sure you are fully aroused. The vagina is unique in its ability to elongate to accomodate well endowed men. But honestly, at ten inches you make never be able to fully accept his entire length, or it may take a long time for you to be able to do so. A lot of that depends on your physical stature. My next suggestion would be to take is SLOW. You may be more comfortable on top, that way you can control the depth of penetration. Having your cervix pounded on while he is thrusting will most likely result in a lot of pain and discomfort for you. Hopefully being a well endowed guy, he is already aware of the physical trauma he could inflict upon you if he did so.
Sex should be about making your partner feel good and sharing yourself with that person. If you feel pain while having intercourse, tell him. Don't lay there and try to take it. Communication is going to be important. If he loves you, he would not want to hurt you and dialogue is the quickest way to eliminate that problem. As a matter of fact, this is a conversation you need to have before engaging in intercourse. Let him know that you are concerned. Set some ground rules - ex: stopping if you tell him to, not thrusting too deep unless you ask him for more.
You will want to experiment with various positions. I don't know how experienced you are, but you have apparently been with at least one other guy. Many women find rear entry very stimulating, and ten inches may be too much and too painful to start out with.
Hope some of this info. helped answer a few question.