The Gift of the Holy Ghost is kinda like having an Upgraded Conscience. He warns you of danger and can lead you away from bad choices. It is also a Promise that as long as you live worthy, He will be your constant companion, a friend that never has to go home. Whenever you need help or guidance in life He is there to give it to you.
So since Fire is a cleansing agent used to purify metals, (Numbers 31:23), the symbolism of the Holy Ghost being a Baptism of Fire is that it cleanses and purifies our souls. This Spiritual Cleansing can, and is intended to, happen continually throughout our lives. Just as we are Baptized by Water and will not be perfect in keeping the Commandments, we will also need a way to continually repent and be forgiven from those sins. This is done by partaking of the Sacrament, or Sacrament of the Lord's Supper. The bread and water are emblems of His Body and Blood, which were willingly sacrificed on our behalf. The conditions that we must meet as we partake of the Sacrament, is that we have a Broken Heart and a Contrite Spirit. (3 Nephi 9:20)
You can learn these things for yourself by reading the scriptures, and praying to know that what they say is true.
Scriptures: 2 Nephi 31:17, Acts 8:38, Doctrine and Covenants 19:31, Acts 19:6, John 14:26, Numbers 31:23, 3 Nephi 9:20, Moroni 10:4-5