Hello I've been coding in c++ for about 3 years and always written my code in one big file rather then separating it.
I felt it was easier but I'm tired of scrolling miles to get to a certain part of the source file so how can I easily and simply split my c++ source files what code is required to do it and what should I split?.
What is quite common is that people make a separate file for every class.
In fact, you create two files for every class: one header file containing the declaration and one cpp file containing the actual definition (assuming it is a not a class template).
If you have a quick google for "C++ header files" or "C++ multiple files" there are numerous tutorials out there on the subject that explain the subject much better than I could.