Now for one of those posts.....
The fact that you are asking for help is a good thing and shows that you are keen to get things right

... however being a firework professional (which you must be if you are obtaining aerial shells), volunteer paid or otherwise you're
work is covered by the HASAWA. You need to maintain competence and this includes relevant training. Competence is one of those funny areas, hopefully it'll keep you from hurting yourself or anyone else, and if it does all go pete tong the ability to prove it might just keep you out of prison. As helpful as folk are on here and as knowledgeable as they may be, a forum does not replace good training.
Paul