Learn these topics:
- Classes
- Class constructors/destructors
- Standard containers (e.g., std::vector, std::map)
- Namespaces
- Defining templates
- Operator overloading
- Polymorphism and class inheritance
- Parameter passing by value, by reference and by pointer
- Const vs non-const
Any good book on C++ will cover those.
Learn C before C++.
When you are good at C/C++ then you can fix as much bugs as you like. Enjoy.