Customer Service developing on a website - chat form

so basically, I am interested in making a customer service on my website. Neither have I tried anything yet, neither have I already made the website.

My question here is, with what, or what exactly do I need in order to add such service, or a function to a website? Just to be clear, the form of the service would be a basic chat concept, messages only, of course.

Of course, I already know HTML, CSS, Python and a decent amount of Javascript. I just thought it was worth mentioning this, that's all.