My 9 yr old son has a small red spot on the ring of his penis head wht could it be?

A few possibilities: It could be an insect bite or just an irritation from his clothing rubbing against his penis. Another possibility is that some smegma (skin cells and oil) built up under the edge of the foreskin (if he is circumcised) and caused some irritation. Keep it clean. Apply a triple-antibiotic ointment. See your doctor if it isn't better in a few days.