opening a port on a D-Link 604

Someone who has come to my forum for my gaming clan has asked if I know how
to open a port on the D-Link 604 which I do not and there English is not so
hot so could someone give me a quick run through on how to do this and also
whats the default way to log on to the router, is it the standard gateway
address and whats the default use name and passoword.

My forum is located at: http://forum.reality-warped.net/phpBB2/ and the user
is ante580