The Gospel of Luke records what Jesus 'began both to do and teach' in His human body, and the Book of Acts tells us what Jesus continued to do and teach through His spiritual body, the church. In the first book, O Theophilus, I have dealt with all that Jesus began to do and teach, until the day when he was taken up, after he had given commandment through the Holy Spirit to the apostles whom he had chosen. To them he presented himself alive after his passion by many proofs, appearing to them during forty days, and speaking of the kingdom of God. The first things the apostles did is they learned from Christ's teachings. Even though Jesus isn't physically with us any longer, we can learn from the Bible and be taught by his Spirit.
Time spent in Bible study and prayer is essential to rebuilding the ministries of our church.
Also notice the disciples believed God's promise for his church. They had never organized a church before or tried to reach people with the gospel message, but they believed the promise of Christ. Notice that Jesus said they would be witnesses in Jerusalem, their local city, in Judea, their province, in Samaria, the surrounding country, and to the end of the earth. We are also called to be witnesses in our city, in our county, in our nation, and to the whole world. Ye shall be my witnesses,' however, does not mean merely that Christ is the object or subject of the testimony, but that the witnesses, belong to him, and that through them the living Lord is prosecuting the work by the power of his divine Spirit.