Step 1: Add the remote (original repo that you forked) and call it “upstream”
git remote add upstream https://github.com/original-repo/goes-here.git
Step 2: Fetch all branches of remote upstream
git fetch upstream
Step 3: Rewrite your master with upstream’s master using git rebase.
git rebase upstream/master
Step 4: Push your updates to master. You may need to force the push with
git push origin master --force