Preconditions:

Rpi2 (Raspbian jessie + tvheadend) connected to your network
TV-Stick (TERRATEC CYNERGY HTC, white) connected to your Rpi2
Antenna (DVB-T or DVB-C) connected to your TV-Stick

Alternative clients:
Windows: VLC and/or Kodi
Android: VLC and Tvhclient
Raspberry: Kodi

Kodi Client Configuration:
install Kodi and enable tvheadend HTSP Client, enter IP-address of your Rpi2 in hosthane field, enter username / password
watch TV :)