Fork today's homework repo, which is an extension of your lab.
Change directories to the lab repository that you worked on in class.
Run
git remote add homework <URL>
where is the ssh URL from your forked repository (what you usually use to clone from, something in the form of "git@github.com:USERNMAE/REPO_NAME.git")
If the 'homework' destination is already defined, instead SET the destination as a new URL:
git remote set-url homework <URL>
git pull homework master
You may be asked to commit a merge. Save and close the merge message.
git push homework master
Now when you push, you'll do
git push homework master
When you're done, issue a pull request from the private-imdb forked repository.