Hi Chisa, There is an exercise called jelqing, you need to google pegym, and on there look for jelqing for beginners, now you keep to what they say, never try and rush our push the program, if you do and go to fast you will end up with ED, your warned, but there are a lot of guys who have gained, all you need to do is look at the photos, surggest you start you own photo album, so you can compare as you grow.
There are many products available in the markets which claim to enhance penis size but unfortunately there are no scientific evidences to support them. Regarding the size I would say that the width, length and erection of the penis vary from male to male. A small penis does not lead to conceptive inadequacy. Only the lower one third of the vagina is sensitive to touch. The upper two third is not. So a longer or shorter penis does not matter at all. Therefore do not worry unnecessarily. Do keep us posted.
Take care and regards!