Bridging two internet networks to use similar network devices

Hey everyone. I'm in a bit of a muddle. I need to bridge two internet networks to allow access to a network printer and file share server. I'm not completely sure how to go about this. Here's my setup:

T1 line-->T1 modem/wireless-->Router-->Printer & file share
DSL line-->DSL modem-->Router

I read about getting some layer 2 switches or some sort but as you can see I have absolutely no idea what I'm talking about. I know how to switch all of that IP and subnet business so there's no interference or whatever, I just need to know what I can do to get the two working together like Jackie Chan and Chris Tucker.