title: How to add existing source and headers file to the CLIon project
body: <p>I am trying to add existing source files to my Clion project, but after adding (Copy and pasting) them to the project, these files were not added to the CMakeLists file. Also, the folder is semitransparent (gray colored).</p>
  
  <p>How can I automatically add new files to the CMakeList ? </p>