Example of how I got this to work with NagiosXI:
1> Configure Nagvis as mentioned previously to enable the link features,
2> In Nagios navigate through Configure/Core Configuration Management/Hosts.
3> Select a host to modify then select the 'Misc Settings' tab.
5> In the name field enter _TAGS. (The leading underscore is required.)
6> If the host is a web server then in the value field you could enter web-80 or web-443, whichever is appropriate.
7> Click on the "Insert>" button and you should see those values applied.
8> Click "Close", click "Save" then click "Apply Configuration".
9> Reload the map that has the host you just edited.
A right-click on that host should now have the option you just added below the options you already had.