Thank you very much Gadev.
Please would you be so kind and help me out a little further.
I have downloaded and unzipped both Eng and Thai files in seperate folders. Do I rename both files gmapsupp.img and place both on SD card and place in my Garmin Nuvi. I would like to have both types on my Garmin. Also what do you mean by (Thai address search function require Garmin XT Thai version and use Thai menu)
Sorry if its all so obvious.