At your level you shouldn't be focused on theory at all. Focus on playing the fundamentals in chess with e4 as white, and e5 as black. Develop quickly, and castle early. Then do lot's and lot's of tactics. Keep on playing lot's of games and happy hunting!
Hope this is helpful.
Josh
i already do all of that why does eeverybody keep aying to watch gotham chess
Look up How to play Italian game from Igor Smirnov or any other opening for that matter. GM Igor Smirnov gives out free opening theories on so many other opening as well. Basically watch a video and know ins and outs of how to get to move 10 without a blunder and at your rating just look at opponent's hanging pieces in first 10 moves. High chance you will see something hanging. Or he will just fall for some opening trap from Igor Smirnov prep.
Book
i already do all of that why does eeverybody keep aying to watch gotham chess
below 800 elo you can probably improve by just playing and learning from past mistakes
What is the best free way to learn Chess theory, I am fairly new to chess and want to improve my rating because I am getting stuck around 600 on 10min.