This is how a baptism is performed.
1238 The baptismal water is consecrated by a prayer of epiclesis (either at this moment or at the Easter Vigil). The Church asks God that through his Son the power of the Holy Spirit may be sent upon the water, so that those who will be baptized in it may be "born of water and the Spirit."40
1239 The essential rite of the sacrament follows: Baptism properly speaking. It signifies and actually brings about death to sin and entry into the life of the Most Holy Trinity through configuration to the Paschal mystery of Christ. Baptism is performed in the most expressive way by triple immersion in the baptismal water. However, from ancient times it has also been able to be conferred by pouring the water three times over the candidate’s head.
1240 In the Latin Church this triple infusion is accompanied by the minister’s words: “N., I baptize you in the name of the Father, and of the Son, and of the Holy Spirit.” In the Eastern liturgies the catechumen turns toward the East and the priest says: “The servant of God, N., is baptized in the name of the Father, and of the Son, and of the Holy Spirit.” At the invocation of each person of the Most Holy Trinity, the priest immerses the candidate in the water and raises him up again.
Best to tell a priest in Reconciliation how you did it and ask forgiveness for attempting/actually doing a baptism without permission of the parents.