T-DSL Internet Connection and Routing

Hi everyone, I'd like to set up an old P200 as a router in my local network. Since I'm using T-DSL, I used yast to set up the internet connection. But I don't know how to start/stop the connection and I don't know exactly how to set up the routing. I guess I have to start configuring the connection first, before I can start doing anything else... after reading some articles on iptables and masquerading I think setting up the connection is the easy part ...and I'm not even done with that :( I'd appreciate every help. Regards, Phoenix