Hi,
If you are referring to the uneven folds of the foreskin collecting dirt, please not that you are expected to clean the head of the penis on a daily basis with clean water after pulling back the foreskin. In any case, do not feel shy to get such doubts clarified from your family doctor even if it becomes necessary to go through your parents. This is all a part of growing up process in a society and remember even your parents have gone through this phase in their life, so do not feel bad about it.
All the best,
Solace
Guidance given by Solace is perfect. Follow it and get rid of the problem. Everyone encounters sexual issues in some way, ignoring this problem puts in great trouble.Treat the issue as a general health issue and take guidance form medicos.