This page deals with configuring a wifi router to work with a DSL modem.
When a separate router is used with your NCF modem, the typical setup is to put the modem into Bridge mode and have the router do the user authentication. The name of that authentication setting is called "PPPoE."
You should be able to configure your router by simply connecting the unit to your computer with an ethernet cable, and accessing the built-in configuration page though your web browser. The address for the user interface, to be entered in your browser's location bar, is often written on the bottom of the unit, or in the router's user manual.