Are you joining an Airport base station or another manufacturer?
Do you have any other machines connected to this network?
Can you get to the config pages for the router/AP?
I don't really understand why you don't want to post more details, but...
You shouldn't need to enter any of the stuff you asked about in your first post. The router should (most likely) be set up as a DHCP server. Once you join the network, all those things get auto-config'd. Just make sure that in the Network pref pane, under Airport, Configure is set to Using DHCP. That's it.