Once you open the Hammerhead app, it will detect your current location and set it as the start point.
If you press for a while on any point in the map, a round monocle appears that you can move to any desired location and set it as the next point in the route.
Every new point you add will be considered as the destination and the previous points become Way-Points. When available, the app shows you an additional route between the points to choose from.
It is not possible to have the same exact point as the start and end of a route.