First Clone Fork
Clone the forked repository in your local PC as below
Adding Original Project Repository to Local Remotes
Add Upstream(Original Project Repository) to your list of remotes as below
Whenever to update fork with the latest upstream changes, first fetch the upstream repository's branches and latest commits to bring them into forked repository:
Checkout forked master branch and merge the upstream repository's master branch:
If there are no unique commits on the local master branch, git will simply perform a fast-forward. However, if you have been making changes on master you may have to deal with conflicts. When doing so, be careful to respect the changes made upstream.
Now, your local master branch is up-to-date with everything modified upstream