Hey guys i'm new here, but i learned the butterfly in kung fu when i was maybe in grade 1, i only started doing them again last year... so i'll try my best
so, here we go
1) this is not required but for beginners it may help for momentum so you can get those legs up; say...your direction is to the left and you will turn counterclockwise, do a little hop to the left using ur right foot (the pixie hop

)
2)putting ur left foot down maybe a little more than shoulder length apart
3)bring your arms back a bit and swing your upper body down following a sort of U
4)when your upper body starts goin up again sweep your arms forward and swing ur right leg up hard while at the same time pushing off with the left foot
5)in the air it'll kinda be like those front float starry things that ppl do in the water and remember that the straighter you keep your legs the cleaner the move, the left leg should follow the right leg (it does for me anyway)
6)upon descent pull your right foot down and this allows you not to crash YAY! cuz crashing suxxors
Things to remember: swing that right leg hard on take off for momentum and air, the arms and upper body mechanical work is also really useful to torque yourself around and provides additional momentum, keep those legs straight!!!
now i gotta work on that b-twist
good tricking sites: yes
www.bilang.com is super
www.trickstutorials.com is also a good alternative, the got backflip, aerial, butterfly twist(btwist), doubleleg, etc etc so check it out
i hope this helps ya and good luck all (i really wish i had media to help)!