I'm not an acting teacher, I haven't studied acting. My resume lists Lee Strasburg and George Loris as acting studio credits, but I'll confess to taking those terms as a means of studying acting culture (I thought there could be pertinent information within that once gleaned could help me land acting jobs - I was right) and not so much to study what acting is all about.
I don't think anyone can teach what acting is all about because I don't think anyone knows. I do think, knowing what acting is all about isn't important to getting parts. What follows are a few things I'd suggest you think about when going for a part, via an audition.
Try not to act when you read at an audition. Try to simply read the lines. It's natural to think that simply reading the lines won't be enough, but in most cases it should be. Read the lines simply and clearly, and with enough volume to be heard by those who're choosing who'll play the roles.
Trust is important. Trust yourself, the playwright, and the director.
Trust yourself to realize you're as capable as the next person to play the role, and understand if you're not cast, it's not because you suck at acting, it's because of lots of other things that are out of your control (too short, too good looking, not good looking enough, wrong color hair, the list is endless), so don't ever fret.
One of the main reasons you might not be cast in the role is, in community theatre, or in any other acting/performance related world come to think of it, the person who gets the role has had a prior relationship with the production. It can be a bummer to lose a role because of so-called theatre politics, but of course, theatre politics can also be why you get a role. Eh?