Did you see my last reply?
I explained this to you. In short you are taking the information the computer is already using and entering it as static.
You need to Click the start button and if windows xp choose run, if 7 or vista type cmd and press enter.
In the command prompt type ipconfig /all
and press enter.
Make note of the default gateway IP and DNS Servers IP's and IPV4 address and subnet mask.
Next Click the start button and if windows xp choose run, if 7 or vista type ncpa.cpl
in the search box and press enter.
Right click on the computers network connection and choose properties.
Next click internet protocol 4 and click properties on the bottom right.
Select use the following IP address.
Fill in the information you got from ipconfig and click ok.
The information from ipconfig /all is what you will use for all of the information you are entering.
Your router is pulling the information for the IP from your modem so the only thing you need to do on the router is port forward. Here is a video on doing thathttp://www.youtube.com/watch?v=wo6dpDZXg7g
Here is another tutorial on doing this:http://www.cctvcamerapros.com/D-Link-Port-Forwarding-s/286.htm