Net neiborghood – browsing domains

We have a pdc and bdc hosted at site A, and a number of identical NT servers, PDCs at our branches; each of these remote LANs have their own domain and no BDC; also they have their own shares and user databases which is a pain for administration. These branches are connected via Frame Relay

What I want to accomplish is to be able to browse (network neighborhood) those remote domains from site’s A domain and make available some shares to the branches and of course include security to them.
How do I need to setup the TCP/IP for each server?
What are the steps to do this? where can I find them?

This is what I have:
Site A domain: domainA
remote branch domain: domainR_xx (xx being a #)

Elliott