How to find IP address of router connected to another router?

How to find IP address of router connected to another router?

I'm trying to setup two routers in my home network, and I'm confused here.
My system looks like this:
http://i.imgur.com/U3dK2SQ.png
So the router 2 is connected to the line. And I'm (my PC is) connected to
router 1. When I type 192.168.1.1, I connect to router 2's config page. So
how can I connect to router 1's config page? I tried ipconfig in Windows'
CMD, but it does not help.
So how can I find the ip of router 1 ?
Note:
192.168.1.2 says Forbidden
You don't have permission to access / on this server.