BIBLE READING: ACTS 1:8-11
This was the very last conversation Jesus had with his disciples before he was taken up into heaven in bodily form. He asked them not to leave Jerusalem until they be endued with power from above. He further goes on to instruct them on what they must do with the Holy Spirit power. He told them to use it to be his witness in all the Earth. This instruction isn't for just them alone, it's for all the Lord our God will call. (Acts 2:38-39).
A witness testifies to what he has seen and heard, and this comes through being in the presence of and encountering someone. It means that the Holy Spirit baptism must bring us to encounter the presence of God, thereby giving us something to testify to.
As a believer who is filled with the Holy Spirit, you must seek out a relationship with the Holy Spirit, with that we can have a testimony for the world. Realize that God's commission to all of us is to reach the whole world with the message of Jesus Christ. Jesus is still in heaven but the Holy Spirit is on Earth with us, he will work through us to execute God's will.