QUESTION: What’s a good way to describe events going on that no one is aware of? Do I do a prologue explaining it? It is important the reader understands the context of the story I'm telling.
One narrative choice is to have a prologue that's strictly overview, kind of like the scrolling words in the first STAR WARS movie. This may work in a sprawling epic fantasy or an historical novel, but it's so old-fashioned that most modern readers won't get past it to get to the real story. For any story that isn't an epic, it absolutely won't work.
You also have the talking heads method where characters who know the overview have a chat about the subject. Again, this is old-fashioned and boring to the modern reader.
The real question is whether the reader needs this "big picture" information, or do you need it to get the big picture straight in your head? Most often, in the case of an inexperienced writer, it’s for you, not the reader.
Readers are smart, and they are interested in what is happening with the viewpoint character--what is his goal, who is thwarting that goal, what are his emotional reasons for doing what he is doing, etc. The big picture isn't so important at the beginning.
Instead, you broaden the knowledge of the main character as he goes along so that he knows why doing what he needs to do is as important to the bigger picture as it is for his own personal story. Or, even better, have him discover that what he wants works against the big picture so he must choose to do the right thing or the selfish thing.