how you should structure your program and stuff you can structure the files something like summative.cbp src (short for source) main.cpp class.cpp include (headers) summative.hpp class.hpp

bum.hpp

#ifndef CLASS_HPP
#define CLASS_HPP //in codeblocks you can just type "guard" then press ctrl-j

#include <whatever>

//if you need another class that you've made, declare it like this
class ineeddis;

class bum {
private:
  int secret;
  
  ineeddis yes;
  
public:

  int return_secret() const;  //if you define something like int foo() const that says that function will not modify anything, you don't really need it but whatever
  
  bum_c();  //constructor
  ~bum_c(); //deconstructor
};

#endif

class.cpp

#include <bum.hpp>  //for the declaration of class_c
#include <ineeddis.hpp> //you didn't say what was in the class ineedis in class.hpp, so do it here

int bum_c::return_secret() {
  return secret;
}

bum_c::bum_c() : secret(1337) {
  //construct stuff here
}

bum_c::~bum_c() {
  //deconstruct, like delete pointers
}

main.cpp

#include <whatev>

#include <summative.hpp>

int main() { //you can structure this however you want, just my personal onions
 init();
 
 run();
 
 cleanup();
 
 return 0;
}

summative.hpp

#include <bum.hpp>
#include <other classes that you make>
//btw .h and .hpp are both header files, doesn't matter which extension you use