If you have not been baptised, that is the place to start. In the early days of the Church, new Christians were often baptised at Easter. After a course of instruction in the faith, they publicly entered into a new life. They repented of their sins, were assured of God's forgiveness and were baptised, often in a river. This was a symbol that they had died to their old life and, born again, been given a share in the Holy Spirit who came on Jesus at his baptism and, after his resurrection, was given to his disciples.
Generally, in the early Christian centuries, those who joined the Church were not only baptised with water: the bishop also laid his hands on them in blessing, a rite which later developed into what we know as confirmation. Admission to the Church was completed by their receiving Holy Communion for the first time.
Baptism, confirmation and first communion still form the pattern today. Some churches still receive their new adult members at Easter.