To unlock the achievement you have to collect explorer badges on all 11 tracks. An explorer badge is awarded for using all available shortcuts on a track in a single race/event, including all free to use and the locked shortcut that can only be opened with a special key. As soon as you have found and used all shortcuts the explorer badge pops up on your screen and you can quit the race if you want.

To keep this guide short and simple it just shows the shortcuts, if you have problems finding the keys and need more information on the locked shortcuts just see my other guide "All locked Shortcut and Key locations" for detailed information about keys and how to use them.