Manual on a Mountain Bike

How to start to manual and then bunny hop.

Steps

Pull up like you are starting a wheelie, do not pedal. Lean back more and hit the rear brake slightly.
Lean back a few times until you are able to determine the balance point. You may have to flip the bike out a few times to find this. If you feel yourself going too far back, dab the back brake. If you are falling forward, lean back more.
Start to bunny hop, but you'll have to do a different style of bunny hop. Start to pull up and jump when you only have one tire/wheel on the ground and that means the rear wheel.

Don't pull up too much
If you lean back too much you may fall off. This may be necessary, but if you are ready for it (determining the balance point) you should be OK.