Before building any website you need to learn about the foundation or backbone of the websites. To build your website you need to become familiar with HTML, CSS, and JavaScript. These are what is holding a webpage together and what defines things such as defining structure all the way to making animated images.

HTML
HTML meaning Hypertext Markup Language is the first and most basic part of a webpage. You can think of this as the structure of a website or like the skeleton in anatomy. It defines elements of the website such as classifying something as a title or header.
CSS
CSS or CSS3 is the presentation of a webpage. Unlike HTML that is the skeleton of a human, CSS would be what the person looks like. It dictates things such as font, color, or background color. It is also used to change and help for various screen sizes.
JavaScript
Lastly, we have JavaScript. JavaScript in anatomy would be the nervous system and muscles of a human as it is what handles interactivity. It dictates the behavior of the webpage. It allows you to handle very complex functions and features as well as control media. It should also noted that JavaScript unlike the others is a very programmatic coding language.