Fork this repository by clicking on the fork button on the top of this page. This will create a copy of this repository in your account.
Now clone the forked repository to your machine. Go to your GitHub account, open the forked repository, click on the code button and then click the copy to clipboard icon.
Open a terminal and run the following git command:
git clone "url you just copied"
where "url you just copied" (without the quotation marks) is the url to this repository (your fork of this project). See the previous steps to obtain the url.
For example:
git clone https://github.com/this-is-you/first-contributions.git
where this-is-you is your GitHub username. Here you're copying the contents of the repository on GitHub to your computer.
Go to the directory where you have cloned the repository.
Now create a branch using the git switch command:
git switch -c your-new-branch-name
For example:
git switch -c add-alonzo-church
Add new code or optimise existing code. Now, save the file.
If you go to the project directory and execute the command git status, you'll see there are changes.
Add those changes to the branch you just created using the git add command:
git add .
Now commit those changes using the git commit command:
git commit -m "Commit Message"
Push your changes using the command git push:
git push origin -u <add-your-branch-name>
replacing <add-your-branch-name> with the name of the branch you created earlier.
If you go to your repository on GitHub, you'll see a Compare & pull request button. Click on that button.
Now submit the pull request.