WSUS 3

I have just installed WSUS 3.0 by the user who has domain admin rights assigned, my network background is domain based Windows AD, now when i see computer in ALL COMPUTERS field i dont see any computer of my domain, i have configured WSUS properly and its only computer section left to be completed i cant help myself and i am unable to understand what to do can somebody help me in this regard what should i do, what step should i take to gather all of my domain computers in “ALL COMPUTERS”. please help me out immediate replies will be highly helpful and appreciated.