Where to find the plugin
In the Joomla Administration ("Back-End"), go to Extensions -> Plug-in Manager (1):
You will find the Plugin under "Content - GPXTrackMap" (2). Make sure the Plugin is enabled (3) !
To get to the Plugin options, just click on its name, which will take you to the Plugin Details and Options:
On the right hand side, the options are grouped into so-called "field sets". Let's look at them one by one:
Next: Options - Overview