Unfortunately, they do not bother to see how their page looks in other browsers, and sometimes their pages will not work at all except in the browser the authors are using. While it is fine to use browser-specific features, just make sure that your page still looks OK in other browsers. Remember that, no matter which browser you are using, most people are using something different. Many people are still using older versions, which may not support newer features, and some people actually use browsers besides IE and Netscape. You can use a tool called Browserola to see how your page looks in various older browsers.
Some providers also give their users their own, usually defective, browsers.
It is best to test your pages on a variety of browsers, to make sure that they work on all of them. Also, even the same browser version may render differently on different computers. Remember that the most important thing on your page should be the content. After you have created your web site and uploaded to NetWizards' web server, you will probably want to register it on the various search engines. Fortunately, most search engines will automatically list you without you having to do a thing, but, you can often register your site manually to get it listed more quickly.