Your router would have come with some form of documentation telling you how to access the settings. Usually, you'll connect to http://192.168.1.1/
and then use whatever default login that documentation tells you to use (usually blanks or admin/admin or something basic like that). For more router help, check http://www.portforward.com/
As for using different ports, not all networks allow you to use ports other than 6667.
Try /server irc.servername.net 6668
(obviously, change the server info)