Firefox includes a search bar, which uses Google by default. Clicking the Google icon will let you choose between Google, Yahoo, Amazon.com, Creative Commons, Dictionary.com, and eBay, and there are also modifications/extensions that will allow you to use Ask Jeeves and others as well. (Just select ''add engines'' from the bottom of the list.)
It should provide an easy-to-use search feature by typing in your search terms then pressing enter/return. The tab you are using will automatically load the search engine's results, preventing you from having to load the engine's homepage to perform the search. If it is not working properly, try using another engine, and if it still doesn't work, you may need to reinstall Firefox. Just use Add/remove to uninstall it, delete the Firefox folder from local drive:\windows\program files, then install the program again. All of your favorites and settings should remain, but any themes and extensions will have to be reinstalled.
Hope this helps,
John