Some guys need to learn how to last longer. Others just can't last that long the first time. You can help him with both problems.
If he just isn't experienced. Try to tease him a little, but when he gets worked up, pull back a little and leave his penis alone. Allow it to get used to the attention. Don't let him come so quickly. If he starts getting excited.make him stop thrusting. Keep him completely still. when the urge to come passes.he can start thrusting again. the more sex you have, the more you work at it, the longer he will learn to last.
If it is the other problem though, most guys can last a whole lot longer after he cums once. If the first time is really really quick, then try giving him a bj first. After he cums, keep sucking him off until he is hard again. When this happens, get on and go at it. Chances are he will last much longer for you, and he will be delighted that sex wasn't over in a few minutes.