Before he sent the disciples forth, Jesus invested the twelve with power over unclean spirits as well as with power to heal the sick. He commanded them to make their journey on faith, depending for food and lodging on the kindness of the people to whom they ministered.
For some time, the disciples had been constantly in the presence of Jesus as he taught and healed and brought other miracles. This period had been for them a time of training for the task they would eventually be asked to take over. How well had they learned the lessons that their Master had taught them? Mark records that they had indeed learned them quite well...
They went out and preached that people should repent. They drove out many demons and annointed many sick people with oil and healed them. (Mark 6:12-13)
With this report, Mark brings to a close the public ministry of Jesus in Galilee. Later he does give us a brief word which seems to indicate something of the satisfaction the disciples felt in making a report of their activities after the preaching tour in Galilee was over. And the apostles gathered around Jesus and reported to him all they had done and taught. (Mark 6:30)