A 180-flip is a kickflip and a 180 shove-it put together. If you know how to do both of those tricks pretty nicely, you'll get this pretty fast. You have to position your feet as you would in a kickflip, except that your leading foot should be hanging off by about an inch. Then, that pop an ollie, move your trailing foot to the heel side, kick your leading foot off the board to the heel side, let it spin, and land. This is one of those tricks that come differently to everyone. It might take you two days, it might take you two weeks.
180 flip