Smegma is a natural "waste" material produced inside the foreskin. It is composed of secretions mixed with shed cells of the mucosa. Normally, it would look something like a soft cheese. It could form as a film over the entire glans, or it could be in little curds nestled in the sulcus (groove). The color could range from white to yellow, and it often has a distinct odor. If left long enough, the odor resembles some cheeses.
Daily rinsing with clear water keeps it under control, but in reality, nothing need be done about it, as normal sexual activity clears it away.