How to use engines to improve my game (weak amateur, not a top player) Once, I played a game against an amateur player, who played really well. When I asked him where he'd learnt to play that well, he merely said that he had used Stockfish to reach that level and had had no formal coaching.
So I got Stockfish and Komodo, the best chess engines, I believe, along with Arena as a GUI. While I clearly see that the engines are really, really good at chess(they beat me easily), in what ways can I use them to improve my game?
To make my question concrete: what are the ways in which a weak amateur chess player can use chess engines to improve his/her game? So, not an expert and not a top player.
My thoughts
I'm not sure of what the answer could be, but maybe it could include something like using engines to develop a sound knowledge of openings? That needn't be the answer, though, it's only my speculation.
It's super hard to get better using chess engine. Those are only tools to help you verify if your calculation is okay. So let's say:


You can check if you saw all the variations that may happen after your sacrifice
You can verify if you calculated that pawn endgame correctly
You can also analyze your games

BUT... (!)


Do not use engines if you want to improve. I swear. The best way, in my opinion (and not only mine) is to analyze your game YOURSELF. 

Then, you need to draw conclusions. Then you'll know what you need to work on the most.


Endgames
Openings
Calculation


Some great player (don't recall who) said you can learn the most out of endgames. But it really depends how advanced you are, i.e. if you are a beginner - don't spend your time on openings too much. We would need to know more information to help you better.