Rich,
to use WM you'll need to have SNMP & CLI ssh credentials (as per my notes).
CLI because some parameters could only be exported by Netsight/WM via ssh CLI commands.
Another thing is that certain settings are exchanged via a langley tunnel - if you haven't changed the default value in the EWC in -> wireless controller -> network -> secure connections ... you are all set.
If you've changed the value you need to set the new one also in Netsight in -> tools -> options -> wireless manager -> shared secret
As soon as you've that configured you should be able to start the wireless manager tool.
I don't use WM tool that often as I don't like the UI - I'm too accustomed to the controller UI.
A nice tool for a deployment with many EWCs is the adaptive UI (which is a part of WM).
Here a screenshot - so on the left you get a tree with your EWCs and one the right the embedded UI for the controller that you choose in the device tree.
So you don't need to have many browser windows open to manage your controller deployment.
Change the link with your own IP to give it a try -->
https://
:8443/wm/jsp/manageControllers.jsp