“See” my other 2 domains

I have 3 domains separated by routers with different IP#(Fictitious)2nd set only is differentDomain 1- router 111.01.222.333
Domain 2- router 111.02.222.333 Domain3 – router 111.03.222.333 . Each domain has its own PDC last # is 3. What do I have to do to “see” these domains on Network Neighborhood or server manager so That I can administer them. I have tried a trust relationship but It can’t find a domain controller.
Any ideas? Try to be specific.
Thank you
Merv