Acts 15:22-35 The Council decision is documented and released

Acts 15:22-29 The council writes a letter. Since this was obviously a persistent issue for the early church, the leadership in Jerusalem decided to write up the decision to ensure that it would be accurately transmitted and preserved. And to ensure that no one would think that it was just Paul and Barnabas bringing this message, they also sent two men from the church in Jerusalem to confirm by word of mouth the letter and the things that Paul and Barnabas were saying.

Acts 15:30-35 The letter is delivered to Antioch (on the Orontes). Judas and Silas from Jerusalem encouraged the congregation with a lengthy message. Whether this was a sermon or a lengthy prophetic utterance is not obvious. After this, they were released, but Silas chose to stay in Antioch. So Paul and Barnabas, and presumably Silas, continued to teach the congregation in Antioch.