Persons wishing to sponsor candidates for the sacraments of Baptism and Confirmation, and those wishing to witness the sacrament of Matrimony, must present a statement of eligibility from the pastor of the Catholic Church they actively attend.
In order to receive such a statement you should be over the age of 16, have received Confirmation, if married - have a valid marriage in the Catholic Church, and are a registered parishioner ( registered means active, that you belong - you have your own unique envelope number, and you are taking part in the parish life). If you are not receiving envelopes with your name on them, your are not a registered parishioner. Exceptions are the elderly sick, or those in nursing homes.
Everyone over the age of eighteen is required to register separately per canon law.
You must be an active parishioner for at least 6 months before you can qualify for any certificate of Baptism, Marriage, Sponsorship, etc.