how to create a git repository in existing folder full of files code example

Example 1: git init repo

git init
git add somefile
git commit -m "initial commit"
git remote add origin https://github.com/username/new_repo
git push -u origin master

Example 2: turn a folder into a git repo

$ git filter-branch --prune-empty --subdirectory-filter FOLDER-NAME  BRANCH-NAME 
  # Filter the specified branch in your directory and remove empty commits
  > Rewrite 48dc599c80e20527ed902928085e7861e6b3cbe6 (89/89)
  > Ref 'refs/heads/BRANCH-NAME' was rewritten