So, I had a friend ask about the set-up of the Priesthood, and I decided to post it here. The Priesthood has two parts, the Aaronic and the Melchizedek Priesthoods. The Aaronic Priesthood has less authority than the Melchizidek and differ in their duties. Once you are ordained to an office, then you still have the authorty to perform the duty of the offices you have already filled, for example, a teacher can perform the duties of both a teacher and a deacon.
The Priesthood is largely in place for service, and these are strictly the basics. If you want to know more about this, visit mormon.org and lds.org for great resources and information. Many of this is also stated in D&C 20 – here’s a link https://www.lds.org/scriptures/dc-testament/dc/20?lang=eng
Deacons: Pass the Sacrament, Collect Fast Offerings
Teachers: Prepare the Sacrament table, including the bread and water
Priests: Have the authority to baptize. Bless the Sacrament.
Elder: conduct meetings, give blessings, administer in spiritual things, have all the authority of deacons, teachers, and priests
High Priest: Preside and hold the authority of Elders.