Hi Michael,
BitBridge is a process that SONAR 64bit will call automatically when you add a 32bit VST plugin from your inventory into a SONAR project.
You'll know if your plugin is wrapped because the window has a blue look to it with a slightly different GUI.
Also, you can find BitBridge.exe in your Task Manager when you have a plugin loaded.
So to sum up, just point 64bit SONAR to your 32bit plugin directories (in Options->Plugin Manager, etc.) and let it scan them. It'll flag them automatically.
BitBridge works pretty well on my setup. Most of my plugins work fine, except for ImageLine ones that it doesn't seem fond of. Better than Cubase's VSTBridge which I think recognised 30-35% of my plugins.
Also look into jBridge as an alternative if you're having trouble with BitBridge. Slightly fiddly to set up, but otherwise a great alternative.