If you don't know the path to a file, simply type the name of the file. If the file is a recently opened document, KRunner will list it for you. If you have the Nepomuk subsystem installed, you can also search your computer for the file by its indexed contents. KRunner will also open folders you've bookmarked in Dolphin (in your Places sidebar) if you type their name in. What's more, if you want to access devices on your system (both mounted and unmounted), you can do that, too. KRunner will even provide device-specific options.
