Once you done all the changes locally, Now the changes should be commited and pushed to the github to rebuild the website. A basic guide about Github, Commits is already explained here

How to Setup Project on Github

• Open Github Desktop App after maing changes or adding new content
• You will see all the information of the changes that you have made agains the last commit.
• Review changes and confirm that you want to make the changes in the code
• Find Summary(required) and Description fields above a button commit to main
• Add the some information about the changes you have done in this commit and press “Commit to main” button. By clicking to the button You have added a new commit/version to the repository
• After clicking “Commit to main” your local repository is now updated with the latest changes but the changes needed to be pushed on the github
• Click on “Push to Origin” Button to make an update on github repository
• Cloudflare will build the website with the new changes