Furuno USA customer units would come with a micro SD card preloaded with all the free USA maps and some others. (Other countries don't get this card normally) Being that Mexico is not in the USA area charted by NOAA, no mapping for Mexico will show up except the base chart which will look like you described (terrible). This is because you basically have no map available. To get a map you would purchase a licence from your dealer. If the TZT2 unit is new enough, it should already have the chart pre-loaded (just locked) on the included chart card. If the unit/card is older, you might want to download the map and update the chip prior to unlocking it to ensure you have the newest map for which you are paying. With all that said, the map you purchased is just fishing bathy from C-map. It has no navigation data. If that is what you intended to buy, you just unlock the chart and swipe up from the bottom of the chart screen and select "FISHING" as your chart selection option. ("Auto" selection doesn't work for fishing it only works for the navigational chart options) With the C-map bathy you need to range down closer sometimes but the bathy lines will be in BLUE. If it had been me, I would have purchased the Navigational C-map chart for that area (which comes with the fishing chart free) so I had a navigational map also.