to connect your modem directly into your router and configure it that way. The router will pass your login information to your ISP each time it (the router) is turned on.
Your router should have full details on how to do this in its setup instructions. One problem that can arise is that both the router and the modem may have a DCHP server running by default. You can only have one DCHP server on a network, and if you find that you have connection problems you may have to disable the server in the modem - let the router do the work.