ResourceManager shouldn't be needed unless you're loading from an external resource.
For most things, say you've created a project (DLL, WinForms, whatever) you just use the project namespace, "Resources" and the resource identifier. eg:

Assuming a project namespace: UberSoft.WidgetPro

And your resx contains:

resx content example

You can just use:

Ubersoft.WidgetPro.Properties.Resources.RESPONSE_SEARCH_WILFRED