Learn to keep stroking
Start to stroke your cock a little until it's hard. Then apply some lube to it. Good, now more lube ... more, it should be very slick. Belief me lube is your friend, it reduces the friction and makes it easier for you.
Okay now start stroking that lubed cock with your hand, but don't rush it, be gentle. Do it slowly, real slow, so slow that you know you can't reach the edge that way. Even if it takes 5 seconds for you hand to slide up your cock and 5 seconds to slide down. But never stop to move your hand, just go real slow.
It should be just fast enough to keep your cock hard, but it's not getting your anywhere. If you feel that you are getting more aroused, slow down, i don't want you even near the edge. I just want your cock to stay hard, and you stroking it all the time.
If you think you found a speed that works for you, keep it up for 3 Minutes, it should just keep your cock hard, nothing more. When you've done that, we can ...