Acts 1:1-11 is not just about the promise of the Holy Spirit, but also his work in missions. The Apostles of Jesus Christ are to be the foundation of the early Christian church with Christ as the cornerstone (Ephesians 2:20); but these are men who were used by the Holy Spirit in an extraordinary way.
When Christ had completed to train them for ministry; he gave them a clear instruction not to depart from Jerusalem until they receive the power of the Holy Spirit (Acts 1:8). The Holy Spirit has been promised by Christ whilst still on his earthly ministry. We read in John 14 about the coming of another Helper and Teacher - the Spirit of Truth who is here to teach the believers everything that Christ would have taught them (John 14:26). Apart from the indweling work that the Holy Spirit does in our lives (God in us), he is also involved in missions. What is the role of the Holy Spirit in missions?
(1) God the Holy Spirit is the owner of the work. The church therefore has no mission; but the God of the church has a mission. His mission is to save humanity and bring total restoration to his entire creation.
(2) The Holy Spirit uses human beings as his instruments to advance his mission; hence the instruction for the Apostles to remain in Jeruslaem until they receive the Holy Spirit.
(3) The Holy Spirit is the one who calls and sent people for mission. We will see in so many instances where people were called (set apart) by the Holy Spirit and sent out for missions (Acts 13:1-4).
(4) Those sent are empowered for service. God the Holy Spirit never leaves his church and servants alone. He is forever there to direct, guide and give strength to do work in and out of seasons.
The only comfort that we get from the foregoing is that the Spirit of Life is always by the side of his servants who are faithful in preaching the good news to others. And the Holy Spirit is also there to ensure that those who believe will have life. He works out salvation in the hearts of those who have heard the gospel and are predestined to eternal life.

The Book of Acts is one of the New Testament books that is popularly known as the Acts of the Apostles and was written by the same author of the gospel according to Luke. He was the companion of Paul on his second and third missionary journeys.
The Book provides a detailed description of the ministry by the Apostles but in essence the book deserves to be called the Acts of the Holy Spirit more than the Acts of the Apostles. The Apostles were used by the Holy Spirit to fulfill their calling and responsibility to preach the gospel to the Jews and the Gentiles alike.

Acts 1:1-11 provides a clear description of the continuation of the finished and unfinished work of Jesus Christ by the Holy Spirit through human instruments, the Apostles. These are man who were called and empowered to continue to preach the saving gospel of and about Jesus Christ to the whole world. The work of attaining salvation for his people was completed by Christ when he died and resurrected on the third day; but the work of witnessing to the world about the finished work on the cross had to be continued by the Apostles as much as the church of every age is still called to do so until the second coming of Jesus Christ.

Acts 1:1-11 speaks to the following issues: