Networks

Default Gateway is defined as the Route to 0.0.0.0 0.0.0.0, which is basically "everywhere else".

This is an example of a network with 2 routers, 2 subnets and access to the internet.

Main Network:

Router on address 10.0.0.254
All PCs on this network use IP addressing in the range 10.0.0.0/24 (10.0.0.1 - 10.0.0.254).
All PCs on this network use the Default Gateway 10.0.0.254

Second Network:

Router on 10.0.1.254 - Also has an external interface address of 10.0.0.253.
All PCs on this network use IP addressing in the range 10.0.1.0/24 (10.0.1.1 - 10.0.1.254).
All PCs on this network use the Default Gateway 10.0.1.254.

Routes:

On the Main Internet Router the following routes are present:

<destination> <mask> <gateway>
0.0.0.0 0.0.0.0 ISP Provided
10.0.1.0 255.255.255.0 10.0.0.253

On the Internal Router the following routes are present:

<destination> <mask> <gateway>
0.0.0.0 0.0.0.0 10.0.0.254
10.0.0.0 255.255.255.0 10.0.0.254

Chances are you'll have to add a static route for the second network.

Remember that while this covers the IP side of the network it doesn't cover naming, but presumably you have a DNS there.

Hope that all makes sense.

Maybe this link can help you:

http://tinyurl.com/yrim