The first thing to understand that it is quite normal for some men to have small whitish bumps on the shaft of the penis and/or at the base of the penis head.
"Fordyce's spots" are the small, raised, pale or white spots or bumps 1 to 3 mm in diameter that may appear on the shaft of the penis. They are common in men of all ages and a normal anatomical variation, meaning they are not a disease and perfectly harmless.
"Sebaceous prominences" are another variation of small pale or white spots that may appear on the shaft of the penis. They are caused by the hair follicle being close to the surface of the skin. Again, these are perfectly normal and harmless.
"Hirsuties papillaris genitalis" is another harmless anatomical variation with no malignant potential, this time appearing as small whitish bumps at the underside of the base of the penis head. They tend to be more common in uncircumcised men. Again, there is no need for treatment as there is nothing wrong if you have these bumps.
However, it is important to keep in mind that various STD's can cause changes to the appearance of your penis. In these cases, or if you are at all worried about something unfamiliar on your penis, it is best to go to a doctor and have it checked out. Just don't freak out at the first sign of a something on your penis, which may in fact be perfectly natural.