if you have existing project and you would like to add remote repository url then you need to do following command
git init
if you would like to add readme.md file then you can create it and add it using below command.
git add README.md
make your first commit using below command
git commit -m "first commit"
Now you completed all local repository process, now how you add remote repository url ? check below command this is for ssh url, you can change it for https.
git remote add origin [email protected]:user-name/repository-name.git
How you push your first commit see below command :
git push -u origin master