You can click on a nearby city name, to set your approximate latitude or
longitude. Or consult a good map to find your own town's location. X10Sched 
uses an accuracy of tenths of a degree, so there is no point getting fancier
than that.

You can follow your Latitude with N (north) or S (south). If you use neither,
N is assumed; or you can use a leading - for south.

You can follow your Longitude with W (west) or E (east), and note that common 
American longitudes are West! The default, however, is East. You can also use 
a leading  minus sign for West (yes, American longitudes are negative).

Elevation is measured in feet above sea level; or you can use meters and
append an m to the number, as in 400m. X10Sched stores elevation to an
accuracy of 100 feet, so there is no reason to get fancier than that. It
treats negative sea level as 0 and elevations above 25500 as 25500.

Time zone is a number, from -11 to 12. American EST is -5 (sunrise in England
is five hours before sunrise in Boston.) PST is -8.

Daylight Saving Time conversion is available if your locale uses it. X10Sched
use American rules (one hour shift on April's last Sunday and October's last
Sunday.) If you turn this on, your PC clock should ALSO know about DST!

You can use the slide bar to adjust brightness. In the default position, The
code aims for the moment the sun is more or less bisected by the horizon.
Of course, there is light in the sky before sunrise and after sunset. This
allows you to specify how much light is considered dawn or dusk. This can be
especiall useful for people in valleys, when the length of the day is 
constrained by surrounding hills.

Click on the window showing sunrise/sunset time to update it after making
changes (but note that this will also SAVE any changes).

If you have not set your location, sunrise/sunset calculation are wild
appromixations and probably should not be relied upon. Location
information is used only for sun calculations.