I'm a 17 year old teenager who is uncircumsized. I have been able to masturbate without any difficulties; however, when I tried having sex with a girl, sexual intercourse felt a little painful. I then realized the pain was from the foreskin not being able to be pulled all the way to the back to the shaft. Is this normal? How do I make it so that it does not hurt?
You raise two issues, one physical and the other spiritual.
On the spiritual issue: you really shouldn't be trying to become a father at the age of 17. Having sex outside of marriage (fornication) is a sin. "Marriage is to be held in honor among all, and the marriage bed is to be undefiled; for fornicators and adulterers God will judge" (Hebrews 13:4). See: Why Sex Outside of Marriage is Wrong.
On the physical issue: having an attached foreskin is a frequent problem. It isn't the way it should be, and as you discovered, it can be painful. To correct the problem, see: I'm uncircumcised. The skin on my penis doesn't pull back all the way to release the tip of the penis. I think it should, but I don't know if I should see a doctor.