Mind Monitor

How can I tell which brain wave state I’m in, or is currently the most active? Is it whichever is at the top?

Yes - Top / It's not really a thing.
You've have activity in all areas of the brain all the time, just some more than others depending on what is going on.

So in terms of meditation and psychic states, when people use “alpha” and “theta” it’s just the dominate brain wave at the time… aka what’s showing up at the top of the graph, essentially?

Correct.

Figuring out your brain wave state is like tuning into different channels of your mind. If you're feeling relaxed, you're probably in alpha mode. But if your mind's wandering, you might be in theta. Just pay attention to how you're feeling.