How do I update the maps of Garmin Sat Nav?

where can i take my Garmin Sat Nav to be updated??

Here for map updates, but you'll have to pay for the map updates:
http://www.garmin.com/updatemaps

Garmin Express allows our customers to download an application form from the web and install it on your PC. This application is user-friendly, or it helps to update the GPS device or Garmin Express. By using Garmin Express updates you can updates maps automatically and register your devices whenever you install your maps. Garmin express allows updating your device software, maps, backup, restore. If you need any for Garmin Device contact at "+19376304611". Visit here for more information: http://garminus.com/