If you come to WebStorm from an editor such as Notepad++ or Vim, you will quickly recognize that WebStorm is not a text editor. Sure, it has a slick text editor component with autocompletion, code folding, and more; but that's only part of the picture. You aren't supposed to pop a CSS file into WebStorm for a quick edit and be done with it: WebStorm is an IDE, and IDEs work with projects. So the first thing WebStorm wants you to do is to import your existing work as a project. If you maintain a live online site, that means downloading your work and creating an offline project.
The next logical step is to put the project under a version control system, as serious developers usually do. WebStorm is well integrated with several version control systems, including the ever-popular Git. Its VCS menu lets you check in revisions, browse the repository, create and apply patches, and more.
WebStorm helps you start new projects in style, too: It features built-in support for Twitter's Bootstrap framework, for HTML5 Boilerplate, and for a number of other frameworks. When I asked it to start a new project based on Bootstrap, it asked me what version of Bootstrap I want, and then it pulled the framework's official Git repository, unzipped it, and presented me with a project that was ready for me to start working on. In a previous version, I did have to wait a moment before I could browse in the project folder, because WebStorm was busy parsing it. Version 5.0 solved this problem.