Use the Git GUI in the Git plugin.
Clone your online repository with the URL which you have.
After cloning, make changes to the files. When you make changes, you can see the number changes. Commit those changes.
Fetch from the remote (to check if anything is updated while you are working).
If the fetch operation gives you an update about the changes in the remote repository, make a pull operation which will update your copy in Visual Studio Code. Otherwise, do not make a pull operation if there aren't any changes in the remote repository.
Push your changes to the upstream remote repository by making a push operation.