My foreskin will not retract

Well first of all I don't know many words having to do with the penis, so please, just bear with me.OK so when my penis is fully erect, my foreskin does not retract. The hole on the top of my penis is just too small. Another problem is that the meatus? (the hole on my penis) is covered up by the foreskin. When my penis is erect, I have to sort of move the foreskin a little bit to see the meatus. Anyways, when I try to retract my foreskin, it kinda of starts hurting, and I have realized that the hole is just too small. I used to not worry about it as much, but since I am ready to start getting sexually active, I thought this might be a problem?