To treat the pimples on the head of your penis, you can start by practicing basic hygiene with clear water once a day, making sure to clean under the foreskin. If this doesn't improve the situation, you can try using an antifungal cream containing clotrimazole twice a day for 14 days. Your pharmacist can provide this for you and monitor your progress. If you don't see any improvement after a week, it's important to consult a doctor.