On GitHub, saved changes are called commits. Each commit has an associated commit message, which is a description explaining why a particular change was made. Commit messages capture the history of your changes, so other contributors can understand what you’ve done and why.
Make any change in the code editor and you will notice that an up arrow is displayed on the GitHub button. The arrow means that there are local changes. They are stored on your computer and they need to get saved on GitHub. Click on that button to open the GitHub view.
The GitHub view contains the diffs that represent every local change. If the changes look correct, click on commit & push changes to create a commit of the changes and push them to GitHub. Once the commit is pushed, all of your code is safely stored in GitHub!
It's good practice to review your local changes before commiting; just like you review your answer sheet before turning in a test. If you find some changes that are incorrect, you can decide to fix them right away, revert the entire file, or even just commit them so you can make any fixes later.