The walkthrough
The card that shows you around on the first run, how it changes depending on where you came from, and how to switch it off or bring it back.
The first time you open B/side it asks one question, and it is not about you.
Where are you coming from?
Five answers: Media Composer, Premiere Pro, DaVinci Resolve, Final Cut Pro, or new to editing. Pick the one that is true and the editor sets your keyboard to match it.
There is no beginner, intermediate or professional here and there never will be. Where you have cut before is a fact about your history; how good you are is a question nobody answers honestly, in either direction, and being asked to rank yourself before you are allowed to make a cut is a poor way to be greeted. "New to editing" is one of the five because it is the same kind of answer as the other four.
The answer changes defaults and withholds nothing. Say you are new and then drop three cameras in and group them, and you get the multicam surface, the same as anybody. Nothing is hidden until you have earned it.
You can close the card without answering. That counts as an answer — not now — and it is not asked again.
What it does with the answer
Two things.
Your keyboard. Each of the four applications has a preset, which is that application's own keys for every command B/side has one for. Anything it has no equivalent for keeps Avid's key, so nothing is unreachable. See the keyboard for the whole map, and Help ▸ Keyboard Shortcuts… to change any of it.
How much the walkthrough explains. An editor arriving from Premiere gets six steps about the handful of things that are genuinely somewhere else here. Somebody new gets nine, and the extra three are the words: what the two monitors are for, what marking a shot means, and that nothing you do touches the file on your drive.
The card itself
It appears next to whatever it is talking about, with a ring around it, and it is one step at a time.
It never blocks you. There is no dimming, no overlay and no "click Next to continue". The panel it is pointing at still works while it points — you can do the thing it is describing with the card open, which is the only sensible way round.
The keys on it are your keys. A step names a command and the card draws whatever key you have bound to it right now. Rebind Overwrite and the card says the new key the next time it mentions it.
It waits for things to be true. The step about dropping a card does not appear if you already have footage. The step about trimming waits until there is a cut to trim. The step about multicam does not exist until you have a group — so if you group three cameras next month, that step turns up then, on the day it means something.
Switching it off, and getting it back
Escape closes the card for now. It will be back next time you open the editor.
Stop showing these closes it for good. It declines the steps you have been offered — not the ones you have not, so a group made later still brings its own step with it.
Help ▸ Walkthrough starts the whole thing again from the beginning, at any point, on any project. What it says then depends on the project in front of you rather than on the one you had when you first opened it.