i just hoped and spun pretty fast. i would practice getting your bunny hops super high and once there you just need to spin pretty quick. Word of advise i would have a spoke wrench because your wheels will take a beating. Other wise keep practicing and if you have a smaller bike try that first.
first thing is, you need a good Bunny hop then when you going to spin, look at the way you spinning with your head and shoulder not just your head, some people find it useful to look under thier shoulder(in the way you are spinning)
its a bit more easy to spin the "right" way so if you have your right foot forward you gotta spin left and with left foot forward spin right i dont quite remember how it was so dont take it too seriously... but spin left and right and keep with the side you find more easy to spin.
Faster speed = faster rotation Your Bunny hop is really important so get a good B-hop and then try 180, 180 are not so hard to do on full suspension bike 360 is much more tricky but keep trying and you will make it good luck mate cheers!