Hi Alan,
What error message do you get?
Also what IIS version are you using?
I would recommened instead of using a port number for the site that you create a virtual folder site in IIS i.e yourservername/virtualfoldername or even a sub folder site which might be even easier.
lets say your server / computer name is called "SERVER1" and in your browser you can visit http://SERVER1 and it loads the default site.
Now in IIS create a new site but call this modxtest.server1
Now edit your hosts file on your PC located in %systemroot%\system32\drivers\etc\hosts
add at the bottom of this file
127.0.0.1 modxtest.server1
Now in your browser you should be able to navigate to
http://modxtest.server1