To do power parking you need to find 2 or more cars that are parked fairly close together. Drive towards the cars and just before the front of your car is parallel to the back/front of the first car you want to park between hit your e-brake. You can then slide your car in between the two parked car. When you are starting to learn this it is probably a good idea to not have too much speed when you approach the cars.
To get a perfect power parking you need to make sure that your car is close (but not touching) and parallel to the curb and not touching the car in front of and behind you. If you touch the cars you are trying to park between and set off their alarms it seems that you cannot power park there again