HTML, CSS : This is the basic of web site designing. You must be perfect in html and css for designing the layout of the website.

Photoshop : You must learn Photoshop to create web graphics, giving effects to images. You can also create an entire website in photoshop if you are perfect with photoshop

Fireworks : To create web graphics, Navigation and giving effects to images

Flash : To create animated effects, headers, advertisements or navigation buttons. You can also create an entire website in Flash

Dreamweaver : This is a what you see is what you get html editor. It ease the creation of website. However this is not an alternative to html. You must have a knowledge of html and css anyways.

Javascript : You need to have a good knowledge of javascript to include some interactive featues in your website. The most important is to validate the form, time and date stamp and other such small features on a web page

ASP : Active Server Pages are used to create dynamic web pages. You should be familiar with ASP and have a thorough knowledge to create back end web applications.

PHP : PHP is also used to create dynamic web pages. You should have knowledge of PHP. It can be an alternative to ASP but you can study this as well.

Java : Java in web designing includes Java Server Pages (JSP) Java Servles and Beans. You can consider this as an alternative to ASP or PHP but it depends on what the firm wants from the job seekers. If their requirements is Java in web desining then you should be good at it. ASP and PHP can be used for the same applications you would create in Java.

Other softwares you must be good at are Illustrator, Corel Draw and Swish. They are used to create high quality web graphics, Images and Navigation or an entire website.