a) You can center the map and zoom in to select locations and use this as filter to show only events near to you.

b) If you like, you can give the browser access to you actual position to compute the distance to the tango locations.
If you do so, the browser will ask you to get access. If you confirm this, the browser can store the geo position as Cookie on your computer, if you press save icon. Our Server will use this only for filtering events for you but itself does not store this and also will not track you by the position. Really! We do NO User tracking!