typing localhost in the browser has nothing to do with IIS. Localhost is a "generic" hostname that you can use to point back to your local computer. In your HOSTS file (%systemroot%\sytem32\drivers\etc) you can modify it, add a record called localhost and map it to the IP of 127.0.0.1. Save the file with no file extension. What this will do is any time you try access the hostname "localhost", it will resolve to the same computer you are on.
If you are running IIS on that computer and you only have one website, it should work accept the connection and assign it to your website. However, if you have multiple websites within IIS, you will have to set up hostheaders on each website or each website would need its own IP.
there are alot of tutorials and resources on MIcrosofts official site for iis--> iis.net