These pelvic exercises are proven to be effective addressing erectile dysfunction. It is actually recommended as a first line of treatment before you run off to medications etc. Strengthening the muscles in the genital can help the penis obtain and maintain an erection.
Start by identifying the muscles of the pelvic floor. Stop your stream several times in the middle of urinating. The muscles you squeeze to do this are the ones you want to target. Now to do one rep you want to squeeze those muscles for 5 seconds then relax. Do that 10-20 times. You have just performed a set of Kegel evercises. Now do that 2-3 times a day and you are all set. Check out some more advanced Kegel exercises here.