Once Launchy has been started, it hides in the background. You bring it forward by holding the alt key and tapping the space key. You then type in a few keys of the program you are searching for and hit enter once it has been found. You can also make Launchy dissappear again by hitting escape or alt+space.

The official documentation pdf is available here.

Launchy is developed to run on XP, however you can try downloading the gdiplus.dll and unzipping it into your Launchy directory to get it to run with Win2000.

For further support, please see the forums on Launchy's SourceForge webpage.