Hi!
This is a very good question! Sunspots are regions of strong magnetic fields, where heating is suppressed so that they are cooler and appear darker than their surroundings. Sunspots follow a cycle -- their numbers peak every 11 years, and reach a minimum about 5 1/2 years later. Where they appear on the Sun also varies with time: first they form higher up in latitude (but not as far as the poles!) and gradually they move to the equator by the end of the cycle -- this leads to the so-called "Butterfly diagram" (see attached link). Why they do this, and why they are not at the poles has to do with the way magnetic fields are generated in the Sun. With each solar cycle, the direction of the Sun's global magnetic field flips -- so that for example North pole goes from positive to negative, and the South pole vice verse. One of the manifestations of the evolution and ultimate reversal of the global field is how and where sunspots appear. The exact details of how this happen are still not worked out, although there is some exciting work on this going on (see second link).
cheers,
Sarah
Link 1:
http://science.msfc.nasa.gov/ssl/pad/solar/sunspots.htm Link 2:
http://www.ucar.edu/news/releases/2004/sunspot.shtml