Its only natural to want to do a wheelie. Ever since you first stepped on a bike you’ve probably wanted to look cool riding on one wheel. Well, it is a tad more difficult to perform this trick on a fixie than it is on your huffy you had when you were 10 years old. The main thing to remember when attempting to learn this trick is to lean way back. You need to position your feet and pedaling motion so you can crank really hard, lean back keeping your arms straight. Pull way hard and get the bike to the point just before flipping over and keep it there for as long as you want to wheelie.
In order to get comfortable with this process, I suggest popping a few wheelies to where you flip right over on purpose so you can get used to it and how far exactly you can go back without flipping over.
Watch this video on how to wheelie, this guy gives some good tips as well.