Change the default search engine in Safari for Windows or Safari for Mac and use your preferred service to conduct your Web searches. You can't add new search providers to Safari in Mac OS X or Windows unless you install additional extensions.
Safari for Windows
Launch Safari for Windows, click the gear icon and select Preferences from the menu to open the Safari Preferences window.
Select the General tab if it's not selected by default and then expand the Default Search Engine box. Select one of the available search engines: Google, Yahoo or Bing.
Close the Safari Preferences window. The new settings are applied immediately and you don't need to restart the program to use the new search provider.
Test the changes by looking at the search field at the top of Safari. The default search provider is listed in the box.
To use other search providers, install their extensions in Safari for Windows. If the provider doesn't offer an extension for Safari, you may not be able to use it to search the Web. Some extensions, such as PopSearch and AnySearch, can use custom search providers.
Safari for Mac
Launch Safari on your Mac, click Safari and choose Preferences from the menu to open the Safari Preferences dialog. The keyboard shortcut to open the dialog is Command-, (Command-comma).
Ensure the General tab is selected and then choose a different search engine from the Default Search Engine drop-down box. You can choose from Google, Yahoo, Bing and DuckDuckGo. Unlike other search engines, DuckDuckGo does not track its users.