Put the Soundock into pairing mode, then turn on bluetooth on the iPad Mini (Settings>bluetooth ON). Select Bose Soundock from the list of available bluetooth devices and let them connect. All sound from the iPad Mini should now play through the Soundock - music, podcasts, youtube soundtracks, whatever. In future, your iPad Mini should pair with the Soundock whenever they're both switched on (with bluetooth enabled) unless the Soundock has already connected with another device e.g. phone,. other tablet etc...
HTH Pete