Can't be Penetrated

First of all don't freak out. This isn't an uncommon occurence. If I had to guess, I would say that you weren't wet enough when he tried to enter you. Either you were nervous about your first time, which interferes with sexual arousal (and lubrication) or you simply didn't take enough time for foreplay.

You also need to make sure that you are unconflicted about having intercourse. You sound a bit inhibited to me--referring to his attempt to put 'it' in rather than saying his penis makes me wonder if you have mixed feelings about having intercourse. Any conflict in this area could interfere with your ability to become aroused and wet, as well as cause your muscles to tighten up.

If I am right, you are simply inexperienced and nervous. The nerves interfered with your arousal, you didn't become wet enough, when he tried to enter you and couldn't you tightened up, and now you are totally freaked out, which isn't going to help you relax next time around.

So take a chill pill, relax and the next time you plan to have intercourse, increase the amount of foreplay and use a lubricant. If you still have a problem, which I don't think you will, then we can talk again.