Upload your final project files to this repo, commit the necessary changes directly here or clone it to your local machine IDE then push the updated version back the cloud of github. With the second choice, you may need to follow the following steps:

step 1: accept the lab invitation you received, it will take you to the GitHub Classroom lab.
step 2: you will see a repository link form the lab assingment page, click on the link to open the respository on GitHub
step 3: clone the repo to your local manchine alternatively, you can create a new branch in the repo, or close to local machine or create a new branch on github.
step 4: create of modify the necessary files to complete the lab assingment.
step 5: after making changes, add, and commit then to your local repo and also push to the remote repo.