howdy and welcome
first understand that it is not required that you become Catholic yourself in order to marry a Catholic, (if you are even contemplating marriage yet) but when you do become engaged you will attend formation sessions at a Catholic parish to help you prepare for this serious undertaking, and to assure that you are both ready for marriage. also, so that you can understand what he, as a Catholic, is obliged to promise.
However it sounds as if you are sincere in considering the Catholic Church for your own spiritual home regardless, which fills us with joy. You would call your friend’s parish, or the parish closest to you, and ask for an appointment with the pastor to discuss this. He will tell you, when he gets to know you and your situation, what preparation is required and helpful for you. There is usually a class involved where you learn about Catholic belief and practice, and some time either during that class, or on Sunday after Mass, spent with the Gospels and learning to listen to God speaking to us that way. The class depends on your needs, the time depends on your progress and upon the Church year, and it takes as long as it takes. May the Holy Spirit continue to guide you, and welcome home!
