Download and open the desired *.gadget file. Afterwards a window opens in which you have to confirm the installation. The gadget will appear in the menu and you can drag the clock on the desktop.

To install the clock (1-5) in the desktop a current Flash Player, and Windows Vista or Windows7 (32bit) is needed.
Of course you can use the flash clocks for your website, too.
Other questions and suggestions? Just write in the guestbook!
Have fun!