Well its totally on you how you imagine your website. Second it depends on what kind of website you want to design. Just like website for Banks will differ in design from website for hospitals.
There are lot many FREE CSS TEMPLATES available on the net. Go through their design just to get an idea on designing the websites.
http://www.freecsstemplates.org/[
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Try to learn the web concepts of the language that you intent to use for efficient design.