Burned my penis masturbating with a too warm towel. what should i do?

Basic hygiene: Being adventurous is part of being a man. I hope this is the worst mishap you ever have. Keep it clean. If there are blisters or obvious damage, get seen because of the location. Different people will tell you different things about covering it (a bit of plastic bag) or applying an antibiotic ointment. Try not to scratch it. Until it heals, handle only with the places that aren't burned.

Skin Heals: Skin heals if left alone. You may need to not masturbate and avoid erections as best you can for a day or so, but skin usually heals just fine.