How can i promote my website??

You need to research SEO or Search Engine Optimisation.

It is too large a subject to be covered here, but Google's own guide is a good place to start.

http://www.google.com/support/webmasters/bin/answer.py?answer=35291

Choose your preferred language if need be then you're good to start your research.

Mark

One of the foremost techniques to increase the ranking of your website is SEO. Go only for white hat SEO. The results will be gradual but long term.
To rank better, start with proper On page optimization of all your website SEO tags. Ensure that your pages contain keyword rich H1,H2 tags, a proper title and description which are within the character limit prescribed by Google.

With the ever changing SERP algorithms, now emphasis is more on rich content. So ensure that your website contains rich content which keyword rich as well as not plagiarized.

Periodically monitor your webmaster tools account to check for any errors that might have cropped up and also to keep an eye on the queries on which your page is ranking.

Build high quality backlinks. More than the number of backlinks, its the quality that matters.

Apart from social bookmarking and forum submission, go for classified submissions, directory submissions, Press Release,Submit good quality articles on your subject of expertise to name a few.

You can pay in Facebook in order to advertise your website to your target audience. Be very precise when you define the target audience. Otherwise, you will just spend your money for nothing.

you can go with SEO and Social Media Marketing as well.