[Help] Need Guidance

Hi guys...
I hope you can help me here...
I wanted to learn how to make an emulator for a certain Online game, but I don't how or where to start... (for learning purpose)
I have basic knowledge of C++, and still learning more...
I have a source code for the emulator but I do not understand mostly how the code works or how the server and the client communicate...


Could you please help me by pointing where can I start (like what to learn and what to understand)...

by the way, I am currently learning to emulate a chip8..
this is what I got in searching for making an emulator... they said to learn first how to emulate the chip8 to know how emulating works...
(i hope i could make a decent chip8 emulator and be able to emulate atleast 1 chip8 game)