How do I get started with test driven development?

I've been developing web applications in several languages, C#, Java, Python. But being more or less of a fresher in the industry my testing background isn't great. I've written few unit tests but I still am quite confused about how to go about making it more relevant to the code I write. I'm mainly looking to understand how to develop the intuition of testing code and making it a habit. If you answer specific to how to do this in a language, I would prefer an explanation geared towards Node.js. Also would greatly appreciate if someone could link me to some resources and also talk about how CI/CD fits into the process of automating tests.