Foreskin Restoration.
In the event that you have been circumcised and want to restore your foreskin, here are simple instructions.

Avoiding lubricant, work your penis into an erection. Using lubricant works against the purpose of the exercise since your desire is to stretch the skin and not merely massage it.
You may want do 50-100 PC Flexes to achieve the hardness you desire for this exercise. Once you’re as hard as possible, grab the base of your penis with one hand and pull it toward the penis head. Pull the thin skin of your penis past its head and--when you can feel a good stretch--hold the skin in that position until you start to lose your erection. Work up another erection and repeat the exercise for 10-12 minutes every day.

It takes 2 to 4 months of daily exercise to see results of foreskin restoration.