Ok, I'm going to assume you have XP or Vista. To get your IP of your laptop do this:
XP = Start>run> type cmd then hit enter. In the black box type ipconfig then hit enter. Take note of the IP Address and the Gateway.
Vista = Start> in the search box there type cmd, then hit enter and do the same as above.
Now, open your web browser and type,
http://ipaddress of your gateway i.e.
http://192.168.1.1 then hit enter, you should be prompted for a user name and password, try this combo's
admin/admin
admin/password
leave blank/admin
leave blank/password
Hopefully that will get you logged into the router. Now look for what I said in the first message.
Internal IP is the IP address the router gives your laptop, it will be something like 192.168.1.xxx
External IP is the public IP that att assignes your router, that is how you will access your network, also note this can and will most likely change often.
Server IP is going to be your External IP above.
Good luck.