If you are new to git and github, to make your first contributions, visit this: Hello World.
If you prefer reading, then these are some of the curated resources you can refer:
- Geeks for Geeks: C++ Programming Language
- CodesDope: Passion Matters, Not Age
- TutorialsPoint: Learn C++, Simply Easy Learning
- learncpp: Tutorials to help you master C++
- cplusplus.com: C++ Tutorials
If you prefer youtube videos, then these are the best ones out there:
If you prefer MOOCs, then refer the following:
For any reference on C++ libraries, refer to cppreference.
You can go through the Getting Started folder to read and practice some of the basic programs of C++ and also contribute your own programs (if similar program not already added by someone else).