If you are not a Catholic and are interested in becoming one, this entails several months of instruction and discernment in order to be sure that this is an informed and free decision on your part. Typically becoming a Catholic involves attendance at regular sessions with other adults thinking of taking the same step. Normally this culminates in several adults being received into the Catholic Church at Easter.
The name of this whole process is the Rite of Christian Initiation of Adults or RCIA.
Your first point of contact is your local Parish Priest.
Click here for more information about RCIA