If You Want to Design Your Own template then You must have to Enough Knowledge of the HTML and CSS.Both are the base of Template Creation.You also have Some What of knowledge of the Flash for make attractive Template.You must have Good Designing Grip.You also can use the Ready Made Template Which are easily available on the Internet.You can find number of Template on the Internet.
To start web-designing and making templates, you don't really need to know what every code means as you will gradually learn that as you make more designs. When you start off, you can check out other people's free templates, you can modify them according to your own preferences and web-site purposes. You can start off by making simple templates that may not look so nice, as you move on to more complicated stuff, you will need to use Photoshop to make your website look more appealing.
Designing a template needs proper knowledge and depth in photoshop, HTML, CSS and inovative design skills. You'll get lots of sites with attractive and eye catchy templates. Watch them properly and while designing be careful about the subject matter.