Keep in mind that we also don't just hand out code. You are going to have to show some work in the future as a "best effort" at solving a problem. Just to let you know before you attempt to do a "give me the code please" style post.
As far as the web server is concerned (IIS) that ip address is a routable address for your local traffic. To my understanding, since the client is on the LAN, that's what you'll get for an external address. The external routable (real) ip address will not come into existence unless it is coming in through your routable interface. If you want to test it you will need to view it from outside the network. That's all there is to it.