Here you have a list of the main beliefs Catholic people have. Knowing them in advance will let you understand and decide if you are ready for additional steps after that.
For a Catholic single, the same God who created the world and expelled man from Paradise after the original sin, came to a man called Abraham to prepare a path for the salvation of all mankind. Centuries later, Jesus Christ completed this task. He taught God's message, sacrificed Himself to pay the debt men had with God, and then rose to become the high priest between the Heavens and the Earth, while He awaits the command of the Father to come to Earth again to carry out the judgement day.
But there are some other things that make Catholic religion unique: For Catholics, God is a trinity of Father, Son (Jesus Christ) and Holy Ghost, forming the three are at the same time the same God. Catholics are also well aware of their rites and traditions, and they accept that the Bible was written thousands of years ago and that it must not be taken literally (which is their main discrepancy with other Christians).
Catholics promote a message of love, conversion and forgiveness of sins, but it requires a sacrament to make it effective for the mortal sins. They value the celebration of the mass and the consecration of bread a lot, as they believe that the consecrated bread is Jesus Christ's/God's body itself and a spiritual food for them.
Besides that, Catholics believe their responsibility in the world is not just to preach until Jesus Christ's return. They need to become a living example of it. They also believe they can already enjoy a part of the divine life on Earth, which will be fulfilled after judgement day.
The Catholic Church is an organized body and the biggest organized religion worldwide. It subdivides in bishoprics, dioceses, parishes and has a responsible priest for each of them. It also has very strict rules when speaking about sacraments and very strict ways to value if something is a sin or not.