...can someone tell where i am going wrong please...

my wife and i are going to canada for her 65th and i have been given my son's old garmin 610 and a friend gave me a file called

'gmapprom.img' for Canada

i have a 1gb sd card and he told to create a folder called 'garmin' on the card.

I placed the file into the folder and then put the card into the nuvi but cannot see the "canada' map...

what am i getting wrong please?

thank you for any help or guidance