The way I learned how to do it:
Just to get used to the motion:
Have two spotters on each side of you when you go up. As you run towards the wall place your arms on their shoulders and leap for the wall about nipple/head height and kick off of it, tilting your head back to spot your landing. You can either tuck your legs, or just swing them, it's your preference. Once you land, do it a few more (dozen

) times to get used to the motion of the flip.
Now do it:
Same thing, except remove the spotters completely. This time, you will need about twice as much confidence though, as this skill can kind of freak you out if you're still not real used to it. Run casually up towards the wall and place your foot on the wall as stated above. Swing your arms and head back and spot your landing while either tucking or bringing your legs over with you and land it. You will probably land on all fours the first few times, but it gets better with more repetitions.
Some of this has probably been said before. Sorry if it has.