Once you click on the link for Texaco/Tomtom, a zipped (compressed) file gets downloaded to a location you select on your computer.
You then need a utility to extract the contents of that zipped file to the specific map folder on your unit. So, use WinRar or Unzip or whatever to extract them, either directly to the unit (assuming the unit is connected to the computer) or to a location on your computer (\temp folder, maybe?) and then use Explorer to copy them to the specific map folder on the unit.
There are 3 different types of ov2 files (and 3 associated bmp's) in that download. So you would extract all six files to your specific map folder.
Then, in your unit, Manage pois. show on map, you'll see the 3 different types listed. Just check them off and they'll show on your map.
Once you've done the extraction, you can delete the .zip file, if you wish.
But make sure everything shows at it should, first.