Welcome Mayank to the Fortran Discourse and Fortran-lang community!
If you want to contribute to the flagship projects fpm, stdlib and Fortran website, there are “Contributing” links on this page:
If you want to contribute in the projects of the members of the community, many people have GitHub or GitLab repositories and will be happy to have a new contributor.
According to your knowledge and skills, you can contribute to small projects or big projects, even to the opensource compilers LFortran, GFortran or Flang (LLVM).