If you want to contribute to an open-source project on GitHub, you’ll first want to fork the repository by clicking the Fork icon at the top right of the repo’s page:
This create a forked copy of the master repository on your GitHub account. You’ll then want to locally clone your copy.
From your forked repository’s page, click the green Clone or download button, then copy the clone link (choose SSH or HTTPS, depending on which works best with your setup — check out GitHub’s help docs for more information).
In your terminal, run git clone [paste in the clone link that you copied from the forked repo].
Create a new branch
It’s important to create a new branch of the repo after forking and cloning so that any work that you do on the code will be isolated from the master branch.
To create a new branch, make sure that you’re working in the directory of the repository in your terminal (you can cd into the repo after cloning it), then run git branch [name of your new branch.
Make the name of your new branch descriptive — let other coders who are working on the repository know what you’re working on with your branch.
After creating the branch, it’s important to run git checkout [your new branch's name] to switch into it. Then all of the work you do will happen on that branch.
Submitting a pull request
Make any changes or additions to the code, then add those changes to the branch you’re working in using git add and commit the changes with a descriptive commit message with git commit -m.
Push your changes to GitHub using git push origin [name of the branch you're working in]. At this point, when you visit your forked copy of the repo on your GitHub account, there will be a green Compare & pull request button. Click that button, and a window will open that will allow you to submit a pull request to the owner of the master repo.
Add a title to your pull request and helpful details that outline the changes or additions that you made to the code, and click Create pull request.
That’s it! The owner of the repository can now review your pull request and merge your changes and additions to the code into the master branch.