Place the lower crank pully indicator toward the top of the motor. There is a small indicator mark on the pully and on the block. Then place the cam arrow indicator (near the #1) to point straight up at the indicator on the head(you can verify this as number one by taking out the #1 spark plug and use a flashligt to see the piston travel). Place the belt on all pulleys. tighten the idler pully just enough to hold the belt tight. Then use a 21mm socket to turn the engine over. The belt will move toward the front of the car. You should have to make two revolutions of the crank to make one revolution of the cam. Once this is done (it tightens the belt, so it won't jump around) use a pry-bar to gently push the idler tight. Then tighten the idler bolt.
I just did this last night and learned that if you don't turn over the motor by hand, the belt cannot be tightened, and it jumps all over. Mine went from #1 to #3!!!