don't try the jumping bit just yet, if you can get on the back wheel, release your brake, stay near enough the same position, and lock it again. the longer you can go with the brake off, in this postion the better. when your comfortable with this, try adding a pedal stroke while the brake is off, if your used to wheelying you'll know to pull you weight back as the bike comes forward, for the first few don't worry about your wheel dropping with the first few, but when you can do several small kicks, rolling the bike, locking the brake, balancing the bike again and repeating, get confident with this, (i've found myself trying to do this more that hopping recently, so it's good to have as a habit, looks smoother and more controlled ) then try pulling the bike up with you each time you kick...