Blessings are called "sacramentals" because they prepare us to receive the grace of the sacraments and help us to grow to be more like Christ (see Catechism of the Catholic Church, no. 1670).
Blessings consist of prayer, Scripture, and sometimes a special ritual sign (see Catechism of the Catholic Church, no. 1668).
People are accustomed to seeing bishops, priests, and deacons blessing objects or persons in the name of the Church. Indeed, "the more a blessing concerns ecclesial and sacramental life, the more is its administration reserved to the ordained ministry" (Catechism of the Catholic Church, no. 1669), often with the participation of the local parish community gathered in prayer. Whenever an ordained minister is present, he should be called upon to give the blessing.
However, there are other blessings, like the ones contained in Catholic Household Blessings and Prayers, that can be prayed by anyone who has been baptized, "in virtue of the universal priesthood, a dignity they possess because of their baptism and confirmation" (Book of Blessings, no. 18). The blessings given by laypersons are exercised because of their special office, such as parents on behalf of their children.
Right after telling his disciples to "love your enemies, do good to those who hate you," Jesus instructs them to "bless those who curse you, pray for those who mistreat you" (Lk 6:28). St. Paul echoes the Lord's command when he exhorts the Romans to "bless those who persecute [you], bless and do not curse them" (Rom 12:14). St. Peter urges that each time we are on the receiving end of evil, we should return "a blessing, because to this you were called, that you might inherit a blessing" (1 Pt 3:9).
This is why the Catechism of the Catholic Church tells us that "every baptized person is called to be a 'blessing,' and to bless" (no. 1669; see Gn 12:2; Lk 6:28; Rom 12:14; 1 Pt 3:9).
Like the Lord into whom they have been baptized, parents should bless and pray for their children. Each one of us should remember the sick and those who suffer. Each time we gather around the family table, we should bless God and the food he has given us. On special occasions, we will observe the traditions of the season, sanctifying by prayer and blessing all the seasons of grace that God has given to us.