What is SU4 Setting pocketwizard plus II?

I have Nikon D80, SB-900 Flash, SIGMA EF-530 DG ST flash with hot shoe, 3 unit of pocketwizard plus II. Now please help me to tigger my flashes.

We could tell you, but all that information is already in the instructions you received with the unit, and in much more detail.

Basically you slide the transmitter on top of the camera where the flash would normally plug in (hotshoe). Set the transmitter on the same channel as the receivers, and plug the receivers into the various flash units via a cord (they are extra and depend on the flash you are using).