Learn to skate backward on your in-line skates. Once you've mastered that, you already know the fundamental skills of the 180 jump. Now take it to the next level.
1. Skate forward at a reasonable speed.
2. Bend your knees and crouch down, winding your torso opposite of the direction that you're going to spin in.
3. Jump up and unwind, spinning 180 degrees in the air.
4. Land rolling backward, bending your knees and staggering your skates slightly to aid your balance. Keep your weight directly over your skates.
5. Continue rolling backwards, but be sure to look back over your shoulder to see where you're going.
6. Repeat steps two and three to return to skating forward.
