for what I understood, you want to access to your OSQA installation from Internet, right?. In this case, you will need to use the external IP address with the port 81:
The correct values that you must use is the DNS NAME (so you could use http://XXXXXXXX.cloudapp.net:81) or the VIP Address (so http://PUBLIC_IP:81).
Also, ensure that your Windows Firewall is opened too.
With that, you will be able to access to your OSQA installation.