HS,
The penis grows by cell mitosis.The cells divide and new ones are created which makes your dick eventualy bigger .Your body does this process at a certain rate.There is not much you can do to increase the growth at a cellular level...except spread out your Penis Enlargement throughout the day.It is better to do 15 minutes of stretching at 4 different times of the day than to do it all in one session.The reason is because penis stays elongated after stretching for a period of time and cell mitosis happens over the entire day/night-not just when you are doing your exercises.
If your dick is in an elongated state when cell division occurs and new cells are being made then the new cells are getting their dna coding from the parent cells in a larger than normal state so the new cells are slightly bigger.
This is the basis of DLD's [words=http://www.mattersofsize.com/forum/showthread.php?64036-My-Best-Work-Ever-Penis-Enlargement-will-Be-Changed-Forever-gt-gt-Gain%20inches%20with%20SRT-Theory-and-Routine]
SRT[/words] theory and is explained way better than i could even hope to in this thread
http://www.mattersofsize.com/forum/...est-discussion&p=478877&highlight=#post478877
Read everything Irspow has to say about penis growth for a detailed explanation of how it works.
Good luck to you man!!