From Lago di Dobiacco / campsite follow the easy and wide trail. You can take some smal trails or cycle on the gravelroad. Nothing steep until the turnoff on the last 1km for the 3 Zinnen-trail. Steep and boulders, you won't miss anything good. But you can cycle nearer to the famous 3 Zinnen.
The My Location button shown in the top right hand corner of this page is a multi-toggle button. The first click will show you your location (red circles) and the trail. The second click will track your location (green circles) and center map. A third click will return to the default map view.