You'll need to be able to code in HTML to succeed in a website design job. You might also need to be familiar with XHTML, Javascript, Flash, and other coding languages. It's also possible that you'll need to know how to use graphics-editing software like Photoshop and graphics-creation software like InDesign.
A web designer should know HTML and computer graphics packages such as Dreamweaver, Photoshop, Adobe Illustrator, and Paint Shop Pro as well as have some knowledge of Flash, XML-based Web applications and programming, XHTML programming, and other Web development languages and technologies. A designer should also be comfortable with various operating systems.