1. Consulting a repair manual: A Chilton's or Haynes manual specific to your 2002 Town & Country will have diagrams showing the exact location.
2. Using a parts diagram: Online auto parts stores (like AutoZone, Advance Auto Parts, etc.) allow you to enter your vehicle's information and view diagrams of the fuel system. The purge pump will be clearly labeled.
3. Searching online for a picture: A Google Image search for "2002 Chrysler Town & Country evap purge pump location" might yield photos from other owners who've worked on their vehicles.
Keep in mind that you'll likely need to get underneath the van to see it. Be careful and use jack stands for safety.