Not everyone can do this.
Web development is a term that is often used to describe anyone who "builds" web sites. If that were true, anyone who goes to GoDaddy.com, buys a domain name and uses a template to "build a website" would be considered a developer.
Web development is more specialized than just seeing a site creation through from beginning to end. It is the customized scripting that creates unique user interaction. It is the building of databases and schemas. Web development takes a company's need for broadcasting it's message in an specific way and uses a variety of coding languages to create an online user experience that produces results.
Web development is a process. It is structure, code, and details that make the web the powerful experience that it has become.