Cisco routers

I am currently running two Cisco 2524 routers between to branches. They are connected via a T1. Right now these routers are used just for interoffice connectivity. I have another router at the main branch for internet. What do i need to do to be able to used the internet from the remote branch through the t1 to the other cisco router out to mty gateway router. Right now the cisco routers are using RIP.