Keep the preasure low,do it a few minutes every other day until you get used to it.
After afew weeks rase the preasure a little.and over time (everyone is differeant) your cock feels fuller,heavier and your erections should get stronger.
If you do to much to soon you will have a hard time getting and keeping your hardon. Check out pumpersguide.com check out the home page,theres a directorial for us nubies.