The first step is to plan. Why do you need a web site, what you want to achieve with it, and how that defines the design, functionality, and content.

The second step is the creation of the design, the mockup, and it's approval.

The third step, is the techical work of creating the website internals in HTML, CSS, and the scripts.

The fourth step is adding contents to the site - texts, images, forms and media. At the same time, the site is tested for how the layout and scripts work.