How do I learn to deploy a side project?

It depends on what your side project is/does. If it is in JS, then I'd use a tool like Vercel. If it is any other language and a webapp, look at Heroku. If something else, then do some research.

Do the getting started guide for your language of choice.

Then map the steps you did for that to your app.

Here's the list of devops tasks a PaaS like Heroku can help with: https://www.mooreds.com/wordpress/archives/2312

Right click - publish

Enter

( Visual studio)