The seventh labour was to capture the Creten Bull.
The Creten Bull was the father of the Minotaur
When Hercules arraived in Crete King Minos told him that he would help him but Hercules refued because it wouldn't count towards the ten labours (he knew from first hand exeperience).
Once he had spotted the trail of destruction he just had to follow it. When he saw the bull he creeped up behind it and strangled it.
King Eurystheus was going to sacrifice the bull to Hera but she declined because it indicated Hercules success.