Here is the picture
This is something that happens sometimes with inexperienced people.
The frenulum limits the amount of foreskin retraction. Sometimes it tears, especially if you try to go in too quickly. That apparently is what happened to you.
You need to let it heal.
If I had this problem, I would pull my foreskin forward to its normal position where it covers and protects the head of the penis. I would leave it alone for two weeks with no attempt to retract it.
After that period of time it should be healed.
In the future, use lots of foreplay to get your female partner turned out and lubricated before you attempt penetration. Penetrate slowly and carefully. This will ease the strain on the frenulum.
If your female partner doesn't have much lubrication, then you may purchase some personal lubricant to apply to your penis before penetration.