http://www.youtube.com/watch?v=z3Zsvm... is a video describing how to learn more about the Mormon Church.
The Church of Jesus Christ of Latter-day Saints has the largest genealogical library in the world. This is evidence of the importance the Church puts on genealogical work (now more commonly referred to as Family History). The reason for such interest in ancestors comes from doctrines of the Church. Mormonism teaches that after death, a person's spirit still has the opportunity to learn about the gospel, and accept Jesus Christ as his Redeemer. But in order for him to become a member of Christ's Church, he must be baptized and have other saving ordinances performed in his behalf. This is the job of those who are still living. In temples, members are baptized, or have other ordinances done, on behalf of those who have passed away (such work is said to be done "by proxy"). This gives that person, if he chooses to accept it, the opportunity to become a member of the Church. Every person who has ever lived has a right to make such an important choice. Members of the Church are strongly encouraged to only perform ordinances for people from their own family lines, and to obtain permission from surviving descendants of the recently deceased.
The LDS Church gathers genealogical information in two ways—through people who submit names of members of their own families, and from public records (as governments allow). These two ways of gathering information are called "submitting names" and "extracting names." The work in both of these areas has become much easier with technological advances, especially advances in computer technology. People submitting names used to have to fill out by hand long pedigree charts, and to search for hours on microfilm for the names of their ancestors. This can now all be done on the computer.
The Church also sends volunteers all over the world to find local history records like parish records, vital records (tax and census), military records, and immigrations records. These volunteers take pictures of the records so that they can be put on microfilm or turned into digital copies and stored. The originals stay where they were found, the master copy goes to the genealogical library in Salt Lake City, Utah, and other copies are sent to libraries and individuals all over the world. The Church provides much service, enhancing family history accessibility for people worldwide. For instance, Church members indexed many of the records from Ellis Island, helping to establish that database for all whose ancestors passed through there as they immigrated to the United States.
Many people outside of the Church are now becoming interested in doing their own family history. So how does one get started? The best way to start is by writing down what you know, then talking with parents, grandparents, aunts and uncles, or anyone else who would be able to fill in missing information. After doing this, anyone can visit one of the 3,700 family history centers run by the Church. One can call any LDS Church ward or stake to find out when the local family history center is open. There are volunteers who work at the family history centers who help with the use of available software and equipment. Information is also available on the internet through Family Search.org. Most of the information stored in the Family History Library can also be found here. Also recommended is writing one's own personal history or histories of close relatives. Doing this leaves an irreplaceable legacy for one's descendants.
Information from http://www.mormonwiki.com