Windows 8 start screen UI is completely different from previous version of Microsoft Windows. Microsoft have tweaked the search UI also to suite user need and allow users to use search with maximum efficiency.
Under Windows 8, search results and grouped into three main category,
To search for application, just press Win key and start typing, where as for settings, use Win-Key+W and for files, Win-Key+F.
Here is a Microsoft video explaining the process in details