If you want good network preformance I think you should connect the routers by wires, but it's not a must.
anyway, as dereo says you have todisable one router's DHCP, and leave the other one enabled, then you need to set the wireless settings for each router, then you should set the internet (DSL) connection and finaly check all the settings are good and I think it should work.
hope you'll be able to understand how your routers' configuration works, otherwise you need to find someone to help you.
