My first ever project, is hosted on avrfreaks.net http://www.avrfreaks.net/index.php?module=Freaks%20Academy&func=viewItem&item_type=project&item_id=1555
There is not a lot to say besides what you can see in the video. To get the source code login to avrfreaks.net - (you will have to. If you are programming an Atmel micro already that's a given) and to find a schematic.... Hmm maybe I will paste it up here too.
(diagram drawn 'ona' copy of the spec-sheet for the AVR microcontroller)
See also this digital solar powered clock done in basic on 2 CPUs: