There should be a small search box at the side of the screen, marked search, followed by Go and Search. Just type what you are looking for into the search box and press the Enter key. Or, click Go / Search. See Wikipedia:Searching for more details.
You can also use Google to search Wikipedia by following this link. The Google index will be somewhat outdated, however, as their bots only search on a periodic basis, and may not yet have caught up with our latest edits.
Some browsers allow searching Wikipedia via their URL/Location bar, for example Konqueror, Firefox, and Internet Explorer 7. This is commonly accessed by typing "wp Main Page", but may change according to the browser settings, please check the documentation on whether this feature is in your browser and how to configure it.
It can also easily be added to the URL/Location bar of Opera by right-clicking the Wikipedia search box and selecting Create search.
User:AxelBoldt has created some bookmarklets for Wikipedia searching. You can get them here. That page also explains how to set up a shortcut in Firefox to have Google search all Wikipedias at once.
Finally, if you would like to search for Wikipedia articles in multiple languages, you can try the little-known but very cool multi-lingual Wikipedia search tool (currently disabled).
§May I mirror entire sections of the Wikipedia to my site? How much may I quote?[සංස්කරණය]
You may mirror or quote as much as you wish, as long as you maintain the text under the GNU Free Documentation License. See Wikipedia:Copyrights.
§If I link a word from my site to Wikipedia, am I required to use the GNU FDL for my site? What if I use a small quote (three or four sentences)? What if I quote entire articles?[සංස්කරණය]
The answer to the first question is "no". Linking is not an act regulated by copyright, so the GNU FDL does not apply. The answer to the second is also "no," since it is covered by the fair use doctrine. For the third question, check with your lawyer, or just put the site under the GNU FDL. However, Wikipedians try to assume good faith, so minor copyright violations are unlikely to result in a lawsuit.
§Can I get Wikipedia on CD, or download it for offline use?[සංස්කරණය]
§How do I cite a Wikipedia article in a paper?[සංස්කරණය]
Cite it as you would any other web page in accordance with the normal citation practice the publication you are submitting the paper to follows. Citing the individual authors is not necessary, but you should at least include the date on which you retrieved the article (and ideally the full timestamp from the history).
Automatically generated citations in several standard styles are available through the "Cite this article" link in the toolbox.
§Why are the backgrounds of some pages light blue and others white?[සංස්කරණය]
Encyclopedia article pages have white backgrounds, while dynamically generated special pages, talk pages, user pages, and about-Wikipedia pages have light blue backgrounds. This is intended as a visual cue that you're not in the encyclopedia per se.
§What should I do when I find a factual error in Wikipedia?[සංස්කරණය]
You should correct it. See Wikipedia:Contributing FAQ. Volunteer contributions from those who believe knowledge should be free for everyone make up Wikipedia, and the community is always ready to welcome whomever would like to join.
Because Wikipedia is an all-volunteer project that anyone can edit, errors or omissions can and do creep in. This should be kept in mind when reading; the very nature of Wikipedia means it should not be trusted completely. Articles frequently contain citations of authoritative works where a reader can verify the information found.