Ohm’s law is super important to learn, but the short version you need to keep in mind is never use more amps than your breaker or fuses can handle.
I couldn’t simplify wiring and circuits if I tried, but essentially keep from crossing polarities and using more than 60% of a load bearing circuit capacity and you will at least keep from a fire if it’s wired and soldered correctly insulating areas prone to shorts if any. I skipped over a lot, but those were the basics I had drilled in my head in HS.