How do I clean my penis?

Ok so I've only recently began to pull my foreskin over my head because I never knew I could. Before this I never used to clean my penis head , I didn't even no you had to! When I pull my foreskin back I can just about get it to the rim of the head because of the frenulum , and I get a smell of fish? There is white stuff on my penis , is this semen ? I just washed it in it shower by letting water run gently on my head and using a tiny bit of soap but my head is so sensitive because I've only recently began to clean it and touch it. I felt really sick because of the unusual feeling (not a good feeling) while touching the head and trying to remove the white stuff. Is there any tips or anything to help me?