Install Doxygen on your machine:

• On macOS, using Homebrew

  brew install doxygen
  
• On Windows, using Chocolatey:

  choco install -y doxygen.install
  
• On Linux, using your distribution's package manager.

Edit the docs/CMakeLists.txt based on your project specifications (project name, source folders, desired layout, etc.).

Compile the Doxygen project using CMake:

• Either by compiling the subfolder docs/ directly:

  cd lagrange-project/docs
  mkdir build
  cd build
  cmake ..
  make doc
  
• Or enabling the FOO_BUILD_DOCUMENTATION CMake option in the parent project:

  cd lagrange-project
  mkdir build
  cd build
  cmake -DFOO_BUILD_DOCUMENTATION=ON ..
  make doc
  

Open the generated html documentation:

firefox html/index.html