|MadSci Network: Astronomy|
There's an easy way and a hard way to figure out exactly where the sun (or any celestial object) will be on a particular date, as seen from a particular location.
The easy way is -- as you yourself mentioned -- to use one of many websites or planetarium programs to do the dirty work for you. Examples are:
There are many more websites, plus many programs you can run on a computer or PDA to tell you exactly where to look at any time and date to see any object. I recommend this simple, easy solution.
But, if you really want to know how to do it all yourself, you can try the hard way. There are several very good books which will both explain the mathematics and provide computer programs you can modify to suit your needs. I recommend:
These books will include references to the really technical literature, in case they aren't enough for you. But I suspect that they will be ....
Try the links in the MadSci Library for more information on Astronomy.