Answers for "push to an existing github repo"

git push existing repo

cd existing_folder
git init
git remote add origin https://gitlab.com/abc.git
git add .
git commit -m "Initial commit"
git push -u origin master

push an existing repository from the command line

git remote add origin https://github.com/arjungautam1/JavaFX.git
git branch -M main
git push -u origin main