Based on the information you have provided this feature is not available nor needed. If you have one system and or directly connect to the Internet the managed network is not needed. This function allows you to see the other computers on your local private network and review the status of the OS it's patches and Service Pack Level.
If you do build a local network the firewall should recognize the local IP network and add it automatically for the first network and ask you for any subsequent networks.
If you have a private network and your managed network is having issue we have a few FAQ's that can help rebuild this data.
FAQ Support Page http://service.mcafee.com/FAQSearch.aspx?lc=4105&sg=TS&pt=1FAQ number TS100380F