|Typically with ADSL you have a separate modem provided by the ISP. Alternatively, some provide a "combination device" that is a modem, router and wireless access point all combined into one device.|
If you have just a modem, then it will have a phone cable going in and a network cable coming out. The network cable should plug into the "internet" (WAN, external) port on the router. If you have a "combo" device then you would have to connect to the new router differently so be sure of what you have first.
Some ISP's also assign you a username and password needed to make the connection. This requires you to program that on the routers "internet" port within the router's management interface. If your connection does require the username/password, or you're not sure, contact your ISP's support line and get their help.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.