"Add DVB Network by location" is a good place to start. If the data there is out of date (it may be) then you need to Google your location and transmitter, or copy the settings from a TV that's already configured. It's normally sufficient to state the frequency and bandwidth with everything else set to Auto.
Again, tvheadend doesn't use any channel list created by w_scan, so that's not a surprise if it doesn't work. If w_scan can detect your muxes, you could use that as input to the above step; if w_scan can't detect anything, then you have a tuner problem.
