After Jesus ascended, the disciples waited for the Promise of the Father, which was the baptism with the Holy Spirit. The Holy Spirit has three presences in the believer: He's with us (beside us), in us, and is poured upon us (baptized with). The purpose of being baptized with the Holy Spirit is for boldness - to be a bold witness for Jesus with courage and power. There is nothing to be afraid of. It's important to realize that the Holy Spirit is a person who has feelings and is not a "force." He, the Father and the Son are equal but separate. There is no formula for being baptized with the Holy Spirit but there is order.