Where do I go in Cubase 6 to rescan my plugins
Are you on Mac or PC?
On PC, To add a third party plugin go to Devices, Plugin Information, VST 2.x Plugin Paths. Add the specific folder path of your plugin (not the entire C drive, as that will cause a crash), then shut down and restart Cubase. Cubase will then rescan for any plugin it can load.
On Mac, if you have installed the plugins on the OS in the proper location (Mac HD, Library, Audio, Plugins, VST), they should load automatically.
What plugins are you missing?