Wow, yes, you are indeed in way over your head.
Go old-school. Borrow every book on home electrical repair from your nearest library. Search amazon for home electrical repair books. There are many available used for a dollar or two, especially in home repair book series' from Home Depot or Black & Decker, etc. Example: https://www.amazon.com/Black-Decker-Complete-Guide-Wiring/dp/1589236017
Read them through, and then read them through again. A 20-year-old home electrical book will not have up-to-date safety code information, but it will at least give you the major concepts and guidelines, and the groundwork for asking more informed and complete questions here.
For outlet issue: an outlet tester is a good first step, but it is only the very simplest tip of the iceberg. There are still all kinds of other things that can be wrong, when the tester shows good. It's like looking at the gas gauge on the car-- tells you if you have gas; doesn't tell you if your transmission is busted.
The outlet tester only tells you if the wires were hooked up in the right order. It doesn't tell you if your circuits have the capacity to run everything you want. Learn about circuit breakers and check the breaker panel for ones that have overloaded and shut off, when the outlet goes out.
Good luck!
Man I hope that box location is okay... that would be amazing. I have a copy of this book; a little old but code doesn't change that fast does it? So that would be a start. Any other online resource for me to check against?