How do I operate the MainStage Garageband controller

I have the AppleScript layout template and scripts installers downloaded. I can see the Garageband template in my MainStage 3's Concerts to select from. I just can't figure out how to get it to work. The AppleScript site where I downloaded it has a video tutorial that doesn't work (at least the link to its video was broken when I've tried it). Does anyone have any simple solutions?

I haven't worked with AppleScript in some time. Right now I don't even see its icon in the Menu Bar on my Macs.

Thanks for any assist