In a previous millennium, when I was a teenager, I did my DoE through school, with the enthusiastic assistance of a number of teachers. Where I lived, the local authority seemed to be very go-ahead, and as soon as I got my DoE, they came knocking on my door (we had no telephone) and signed me up to do instruction and assessment. Ha... can you imagine a local authority conscripting a teenager like that these days?
Anyhow... the local authority sent me off on a residential course, which was great fun, and they told us exactly what was required of us. So there I was... a mere teenager... instructing and assessing other teenagers!
I guess I'd be doing it to this day, except I left that area and the brief contact I had with a neighbouring local authority left me chilled to the very marrow. Actually, the sole person I met seemed incredibly hostile and bitter-minded, and one minute in her presence was as much as I could tolerate, so I walked out and never looked back.
Moral of the story... never mess with a volunteer!
As for the OP's request for information... if they've asked you to help out, then you should expect them to be able to spell out exactly what they want you to do, and give you every support and encouragement to do it.