Here's a link to the Catechism of the Catholic Church. It's a reference book containing what the Church teaches on pretty much everything.
http://www.scborromeo.org/ccc.htm
The basics, of course, are in the Nicene Creed:
I believe in one God, the Father almighty, maker of heaven and earth, of all things visible and invisible.
And in one Lord, Jesus Christ, the only-begotten Son of God, and born of the Father before all ages. God from God, light from light, true God from true God, begotten, not made, consubstantial with the Father, through whom all things were made. For us men and for our salvation, he descended from heaven. And he was made incarnate by the Holy Ghost, from the Virgin Mary, and became man. He was also crucified for us under Pontius Pilate. He suffered and was buried. And he rose again on the third day, according to the Scriptures. And he ascended into heaven. He sits at the right hand of the Father. And he will come again with glory to judge the living and the dead, whose kingdom will have no end.
And in the Holy Ghost, the Lord and giver of life, who proceeds from the Father and the Son, who together with the Father and Son is worshipped and glorified, who has spoken through the Prophets.
And in one, holy, catholic, and apostolic Church. I confess one baptism for the forgiveness of sins. I look for the resurrection of the dead, and the life of the world to come. Amen.
Here's some other Catholic beliefs, particularly the ones where Protestants often disagree.
We believe that the Bible is not all we are to follow, but also the teachings of Jesus passed down orally through the Apostles and their successors, the bishops, guided by the Church and protected by the Holy Ghost.
We believe that Mary was conceived without original sin, by a special favour of God, remained a virgin her entire life, and was taken to heaven body and soul upon the end of her time on earth.
We believe that nothing unclean can enter heaven, so all traces of sin will have to be removed from us, either in this life or the next. Not all sins are so bad as to warrant hell, but that they must all be purged from us before we can stand before the all-holy Trinity. We call this process of purification purgatory.
We believe we are saved by God's grace. Without Him and without the sacrifice of Jesus on the Cross, none of us would make it to heaven. However, we must co-operate with Him. We must believe (faith) and we must follow His commandments (works). Both are needed.
We believe that in Communion, the bread and wine become the Body and Blood of Our Lord. They are not just symbols, but actually Jesus Himself. As such, the Mass is an unbloody re-presentation of the Sacrifice of Calvary. It is not re-crucifying Jesus, but His way of making His one Sacrifice present throughout time. At Passover, the Jews had to sacrifice and eat the lamb. For Christians, the sacrifice was two thousand years ago, but the eating part can only be done by each of us when we are here on earth.
We believe in seven sacraments - baptism, confession, confirmation, communion, matrimony, holy orders, and extreme unction/anointing of the sick.
We believe Jesus commanded us to confess our sins to Him through his apostles and their successors. He gave them the authority to forgive or retain sins; to do this, they must know what the sins are and whether someone is sorry for them.
We believe Jesus established a Church with Peter as its earthly head, and gave the Church the authority to bind and loose. (See Matthew 16). Peter was the first pope, and his successors retain this authority.
On moral issues, we believe war is sometimes justified, if it is the only way to stop an aggressor nation. Whether these conditions were met for the war in Iraq is something Catholics can disagree on. The death penalty can be used if it is the only way to protect society from criminals, but in today's society with maximum-security prisons, it may not be necessary. Abortion, as the deliberate killing of innocent human life, is never moral. Birth control is also immoral, as it can cause abortion, or at least interferes with God's plan for a husband and wife to totally give themselves to each other.
Socially, we should help the poor and disadvantaged. The Church does not endorse any particular economic or political system, but has condemned communism and socialism. Whether helping the poor should be done by individuals or the government is a political question, not a religious one, so the Church does not officially take a position on this, only that we must help the less fortunate somehow.
Hope this helps. There's many other things we believe; if you have specific questions, we'll be happy to answer.