how to increase penis size??

Umm, you can't increase it's size.  It's part of your DNA just like how big your fingers and toes are.

The average is 5 - 5 1/2" for an adult male.  It can continue to grow into your early 20's.

It's not the size, most women say it's what you do with it.  Too big can actually hurt them.

Hope it helps.

You cant have a permanently larger penis.  You can do things to give you the look of a bigger penis.  Trim your pubic hair.   Try some natural supplements like Chinese Doddard or walnut or maca.  You can try a male enhancement product such as Endurnz which has a formula with most of the popular herbs and extracts.  They can give you a harder erection and maybe a bigger penis during sex.  Some people say exercise and stretching works.  Im not sure about them but you could try.  The penis pump will not help you.  it does increase the size of the penis for a hour so so, but it erection is not firm, as if you are young and healthy is might hurt your penis.