Priesthood is the authority that God gives His children to bring salvation to all. Priesthood authority is governed by priesthood leaders who receive and exercise priesthood keys. Since the scriptures state that “all other authorities [and] offices in the church are appendages to this [Melchizedek] priesthood” (Doctrine and Covenants 107:5), all that is done under the direction of those priesthood keys is done with priesthood authority.
When a woman is set apart to preach the gospel as a full-time missionary, she acts under priesthood authority to perform a priesthood function. Anyone with a calling received from someone holding priesthood keys exercises priesthood authority in performing her or his assigned duties.
If you are a Melchizedek Priesthood holder, you will have opportunities to participate in priesthood ordinances and blessings.
For more information see section 7.11, “Priesthood Ordinances and Blessings.”