Virgin here.after puberty i only get rock hard erection when i clench my pelvic muscle or at time of ejaculation. i also have problem of urine drops so i put pressure behind testis and push this pressure towards penis head does this damaged me?

No. What you described is normal. For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. Get HPV vaccine. Wish you good health!

You can relax. with proper stimulation you will get hard erections without having to contract any muscles. When you think you have finished wait a few more seconds and let the last few drops out and make sure the penis is in a dependent position and not bent over the pants fly. Do not do any other maneuvers you dont need them. You'll be fine