php to generate statiscs

Hi list, Sorry if this is a off-topic, but I really don't know where to begin. I have a mysql database with about 20.000 records, now I need to build a statistics panel to show for example how many of this record are male, female, lives in determinated city, school graduation etc, everything grouped by sex and alone too, present the respectives percentages etc... How do I begin??? Can someone help?? thank's in advance Rodrigo Peres