when you got your new router, it would of come with a manual. if not, there should be a cd and the manual is in that. it will tell you how to log into the router. usually, you open a webpage and type http://192.168.0.1
and a password prompt comes up. USUALLY username is "admin" and password is either left blank or its "admin" again. if successful, you will be logged into the router. then you need to look around till you find a dropdown box which displays the channels, USUALLY its set to 6, but that can change. anyway just change that number to anything other than what it is and save it. you should be good to go. these are just the usual cases for logging in to a router. you need to read your router manual to log in.
oh by the way, its a good idea to change the username and the password after you log in. also enable WPA or WEP encryptions so people dont connect to your router and use ur internet or worse... all of this info is explained in the manual.