I have never been baptized
I was raised in a non-Christian faith (Jewish, Muslim, Buddhist, etc.) or I grew up in a Christian household but have never received baptism.
And now I want to become Catholic.
A Catholic / Roman Catholic is a baptized Christian
who professes faith in the Blessed Trinity (Father, Son, and Holy Spirit) as revealed in sacred scripture,
recognizes Jesus Christ as Son of God, who by his passion, death, and resurrection brought about our reconciliation with God through the forgiveness of our sins,
is nourished and nurtured by the Holy Spirit through the grace of the sacraments,
under the care of legitimate pastors in Apostolic Succession in union with the Bishop of Rome
The path to baptism involves a process of discernment with the assistance of the Christian Initiation Team (RCIA--Rite of Christian Initiation of Adults) made up of baptized Catholics who assist the pastor
I am a baptized Christian
I was baptized earlier in my life.
The person who baptized me may have been a minister or not, who either poured water on my head or immersed my entire body in a pool, and used the words "I baptize you in the name of the Father, and of the Son, and of the Holy Spirit." I also practiced the Christian faith for a number of years as a member of another church community.
And now I want to be Catholic.
As a baptized Christian, you are already a member of the Body of Christ. Although you do not yet share full communion with the Catholic Church. your baptismal dignity gives you certain rights in the assembly of the baptized. If you join us for Mass, you have a place with us as we listen to the Word of God proclaimed and preached. You may also take a place among us during the Liturgy of the Eucharist, but should not approach the Table to receive Communion until you are formally received into full communion with us.
Full communion is a term that expresses our sharing in three significant aspects of life as Catholic Christians.
The first significant aspect is our profession of the same Christian faith, enshrined in the Apostle's Creed or the Nicene Creed, which we proclaim publicly at Sunday Mass. Many Christian communities profess one or other of these creeds regularly.