i have website .but i dont know how to design my website.can any one tell me how can design my website?
I'm afraid this question is far too vague to get a proper answer.
Which ones you will need will depend rather on what you want your site to do.
You also need to consider if you want to build it yourself, or use a CMS such as WordPress.
My advice to you would be to find a simple tutorial to follow: http://www.google.com/search?q=simple+web+design+tutorial
Then, if you get stuck with anything, come back with specific questions.
Also, I can highly recommend this book: http://www.sitepoint.com/books/html3/