to not function the "copy" feature if someone want to copy the material on the page
Use Macromedia Flash. I don't think someone can steal you material/images (copy/paste) is they are in flash.
It's impossible to prevent copying from your Web site. There are some things that will stop beginning-level Web users, but they are easy to work around for someone who knows something about how the Web works, and really wants your stuff.
I display my name, date and a copyright symbol in all the pictures that I post on my Web site. You can add them using most any image editor, I use Photoshop. I also never post original full-resolution photos, only down-sized versions that are only good for viewing on a computer screen, not for high-resolution printing.
For text, display a copyright notice on each page, have a clear statement somewhere on your site about what's OK and not OK for people to do with your material, and use Google occasionally to search for copies of your material. Most Web-hosting providers in the USA at least, forbid copyright violation by their users, so if you complain to someone's Web host they can often do something for you.
What is it you're trying to protect?
(It might be text. You could put your text in Acrobat.)
What are you actually trying to prevent? It's unlikely you'll be able to prevent people from just coping pictures. Even embedded in flash they can still take a screenshot (print screen, then paste into paint). If you are trying to prevent people from stealing things you create and passing it off as their own, then a watermark, like jtbell said, is a good method. The bottom line is that trying to prevent people from copying won't stop anyone who really wants it, and will just annoy legitimate users.
Edit: Text is harder, but I remember a site that used to put random links back to that site in the text, as random periods. Like thishttp://www.google.com" [Broken] You can use CSS to make it so that those links don't show up like normal links on your page. It won't stop people from doing it, but if anyone clicks the link (from the content thief's site) it'll let you see the pages stealing your content. Also you can just search for unique text from your page in google with quotes around it.
I was interested in the same. Basically I've heard that if I install flash photo gallery then it will disable my pics form downloading but then it turned out that this is absolutely useless because people can use print scr button and then cut my pics.. I'm at loss is it really impossible to protect images?
Even without print screen, you can use a utility to download flash content from a website. If you don't want them stolen, don't display them in a public place (ie. the internet). Or watermark them so that your name and (c) is part of the image. Or just enjoy sharing. :P
Basically I wanted to sell logos and Corel/Photoshop pictures that I create myself. So I'm not interested people just download them for free...
Just put a big watermark across them.
Better yet, let someone else handle that problem for you.
It's very big business. What you might want to do is decide whether you want to spend your valuable time building a website, or making saleable product (the old saying: " You wanna fish? or cut bait?"). Investigate the clipart repositories already out there who will handle all the business details (including web store) for you. That will leave you to concentrate on the art.
Separate names with a comma.