Help starting up a network

[kenghtt]

Hi guys!
I wanted to create a subnetwork within my main network. My main one is used just for internet and is shared by 4 people (my roomates). It currently has a modem and wifi router hooked up.

I plan to get another router going, so that my personal laptops and computers can be used in it.
My question is that if I get another router, and I try to connect it with the main router, Can my connect my second router without having to connect an Ethernet directly to the main router?

 

[kenghtt]

Forgot to mention, the reason I ask is because the Main router is in the living room, and I want to put the second router in my bedroom.