I ,an environmentalist, want to make some graphs and maps, by using GIS, for a minor project.I have gathered the meterologial data of my city for last three years.This data is all about temperature,rainfall,humidity and pressure.All these statistics are contained in a .xls extension files .I want to make contrast among the figures as per city's geography with the help of map symbology.But I dont have any geographical data. Could you instruct me how to proceed further?