Offtopic/fun » Suggest simple ways for Garmin map update

I am a traveler and often I plan for many small and long trips for most popular tourist places of the world. I have good traveling experience, so I use Garmin GPS unit. With the aid of Garmin GPS unit, I can track the right routes or desired destinations. But from a few days, my GPS unit is not showing the right signal to track the desired destinations. I think that it can be the problems of Garmin map update. I don’t have knowledge to update my GPS unit. So please anyone can recommend the simple ways for Garmin map update.