Hello Ghee. If you go the developer tools in your menu, you will be able to explore the way a site's page was designed. You can also get to this feature by right clicking on your mouse to show a menu and choose to inspect element, for the element your mouse pointer is over. Elements are what makes up a web page.
In the developer tools you can see the outline which is html using < > , known as tags. The style tab which is css using { } , known as curly brackets.
You can build websites using programs as simples as Notepad or Text Edit. These programs have the capability to be an IDE, Intergrated Development Environment, needed to compile and run certain programming languages code.
These tools can assist you while you are learning.