Business Objects Universe on top of BW System

Hi,

I developed the universe on top of bex query as a data source, Then i created some of the webi reports on top same universe. The reports having the four zones data like East ,West, South, North, i want to display the data for East Zone users can access only East Zone data, West Zone Users can access Only West Zone data in webi report. How can achieve the same, any one can give me the solution for this.

Regards

Lingaiah