Anyone know how I can copyright my website? I read somewhere that it costs 150 dollars? is that true?
Your website is copyrighted the moment it is created. Depending on what country you live in you can get additional protection by registering the copyright. The cost depends on what country you live in. Keep in mind that your registered copyright will only apply to your own content and graphics. It does not apply to any info you aggregate from other places, your layout, or your concept. Also, it only applies to what is on your site at the time you register it (though you can usually get additional updates to your registration for additional fees).
If the content is unique to you then you need to ensure you place a copyright notice on the site. (c) Site name, all rights reserved. There is no specific way to prevent copyright theft, there is scripts and software about that will ensure people can't right click on your images, there is also scripts that can stop people copying your content, but they tend to be expensive and only worth it, if your content is invaluable and unique.
what if you have a company and you own a website, do you place a copyright by the domain name and the main companies name? Or mention that this domain is a copyright of the main company?
In the US there is no requirement that you use the (c) symbol at all, since the content is copyrighted as soon as it is created. However the copyright information can be useful in deterring the ignorant from swiping your content. From the US Copyright office: http://www.copyright.gov/circs/circ1.html#noc
By the way you can use www.copyscape.com to find if somebody has copied your content but not the graphics.
@pravin4work wow...i didn't know this website.It's very useful. Thanks a lot What about the graphics ?Do you know ?