Connecting ISA with Domain.. (AD)…

Hi..

i have installed Active Direcotry on one server…. using Windows 2003 Server..
with Users in their respective OUs…

And ISA 2006 on another machine..

Now i want to restrict users from Accessing certain Sites accordingly using their OUs… from ISA server…

Please Provide me Help… Details will be really Appreciated…

With Best Regards…