If you can't afford film school, Tony Zhou's online video series Every Frame a Painting is a good place to start for free.
Zhou presents brief explanations of how films work (often how they work visually) and shows scenes to illustrate his points. In last week's episode, he explored the geometry of staging actors within a scene—the idea is that if actors are doing something onscreen, the director can place them in the "frame" of the screen in a way that demonstrates what's going on visually, adding to what we get from the scene beyond what they say. This is in stark contrast to what director Alfred Hitchcock derided as "photographs of people talking," the visually boring alternative, in which people stand around and talk without doing anything.
If you've got three minutes and any interest in how movies are made, check this out:
And if you're curious about the context of that Hitchcock quote, here's the full 18-minute interview from 1964. (It's fantastic; he also says, "If possible, tell the story visually and let the talk be part of the atmosphere," among other smart thoughts.)
Also highly pertinent: Steven Soderbergh's Raiders of the Lost Ark, an examination of how well Raiders is staged visually, with no need for dialogue or even color.