i have  a web app that runs locally on our network. the way users access it is by going to myserver:80/site/default.aspx
i reconfigured the settings to
In normal case if you are hosting your site in IIS and if you are having your IP fix you can also browse your website through your local ip in your network by address by keeping your 'ipaddress' in place of 'localhost'. Now if you wants to access it from your global ip you need to add binding to the IIS and then it will respond to all the requests.
So in your particular case you need to add binding with your IP (check it from whatismyip.com). Go to IIS -> Sites -> Default Web Site. On right hand side column you will get bindings. Add new binding in it.