The 'Locate' icon can be found in the top center of the main map screen.
It has three modes:
1. Off - icon shows blue
2. Centered on Location - icon shows orange and centers your current location on the the map
3. 'Course Up' Mode - icon shows green with a directional map arrow icon. This mode will continuously keep your location centered on the screen. The map will scroll as you move.
4. To disengage - tap the icon one more time and the icon will turn blue.