Actually, you're mostly going to just configure your code. I've written it all for you.
You can use whatever text editor you want for editing JavaScript, but I like Visual Studio Code and that's what I'll be showing here.
You can download Code for Windows, Mac, or Linux and it's free, so no excuses there. Go to visualstudio.com.
To open your code in Visual Studio Code, you simply change to the tweetmonkey-raspi directory that was created when you cloned the project and type code .. That opens the current directory in Code.
Now we need to transfer the code onto the Pi using either rsync or scp. If you're a Windows user, you may not have access to these applications. In that case, simply add the usr/bin folder from your Git installation to the PATH environment varialbe. This lighs up a ton of Linux commands from PowerShell/cmd.
Be sure you are in the tweetmonkey folder.
To SCP, use...
scp index.js package.json pi@raspberrypi.local
I like to use rsync. Here's how to do that...
rsync -rave ssh . pi@raspberrypi.local:~/tweetmonkey
In both cases, you'll be prompted for your the password to your Pi until you setup ssh keys to make that annoyance go away.
Next, learn how to deploy and run the program.