Thanks for your query.Based on the facts that you have posted it appears that you have undergone surgery of excision of Melanocytic Cyst over your penis and it has complicated in gaping of the wound resulting in to a raw area of healthy wound over shaft of the penis..
Please take broad spectrum antibiotics along with anti inflammatory medication like Diclofenac
twice daily .
Get the prescription of medicines from your family Physician.
Ensure to clean your genitals with anti microbial solution like Betadine
and apply topical antibiotic
ointment like Neosporin
daily.warm water .
It should get healed up within 2-3 weeks.