generally a child under the age of 7 is considered an infant. You would register at your parish, attend the next baptismal preparation classes, as will the prospective godparents, and baptize your child the next time your parish baptizes. the rules for godparents will be explained when you register.
Once the child reaches the age of reason, generally considered as age 7, he is considered an adult for the purposes of the sacrament of initiation, would go through the RCIA, in a class with others of his age group, go through the rites (adapted for children) in due course, and be received into the Church at the Easter Vigil, being baptized, confirmed and receive 1st communion. During the period of mystgogy following he would prepare for his first confession.
See your pastor first, then have an interview with whoever is in charge of religious education, either the Catholic school principal or the DRE. In our parish, unbaptized children may attend the school but are expected to come to RCIA classes through the parish, not the school. There is no problem with him attending Catholic school in the meantime, but they are usually not set up to provide the special preparation needed for RCIA.
at least one parent has to consent, please see your pastor without delay to discuss this aspect, as well as how to proceed.