The Academy of Pediatrics (AAP) says that you should NEVER retract your son's foreskin. This may/will cause problems. Just cleanse like you would a finger. He will retract on his own. He may not retract until his teens. THIS IS NORMAL.
A major reason for the idea that the natural penis is difficult to clean is a small, but feared word: "smegma". It even sounds ugly, so who wouldn't believe what they might hear about it and the non-circumcised penis? Actually, the word itself comes from the Greek smegma translated as "detergent", "cleansing medicine",and "soap". Smegma can be found between the glans and the foreskin and between the clitoris and its hood, as well as between the labia. (Both the penis and the clitoris form as the same tissue in the womb during the first trimester of pregnancy.) In both sexes, its job is to lubricate and cleanse. If it is washed away too frequently, the mucous membranes of these parts can become dry and irritated. The picture that is sometimes given of smegma is of a flowing, cheesy substance which smells. (I picture feta cheese, myself, when I hear this comparison!) Frankly, if smegma were to be allowed to build up to this amount, the man or woman would surely know about it before it began to smell, as going that long without washing would make one itch - and not only in the genital area either! In actuality, it is a whitish, pasty substance which doesn't really have much of an odor. It does not "flow" and is easily removed with a rinse with water, or soap and water if one prefers.