I don't think it can be said any more clear then these two videos.
Here is what the Prophet has asked us to do:
The following letter was sent from the First Presidency of The Church of Jesus Christ of Latter-day Saints to Church leaders in California to be read to all congregations on 29 June 2008:
Preserving Traditional Marriage and Strengthening Families
In March 2000 California voters overwhelmingly approved a state law providing that “Only marriage between a man and a woman is valid or recognized in California.” The California Supreme Court recently reversed this vote of the people. On November 4, 2 008, Californians will vote on a proposed amendment to the California state constitution that will now restore the March 2000 definition of marriage approved by the voters.
The Church’s teachings and position on this moral issue are unequivocal. Marriage between a man and a woman is ordained of God, and the formation of families is central to the Creator’s plan for His children. Children are entitled to be born within this bond of marriage.
A broad-based coalition of churches and other organizations placed the proposed amendment on the ballot. The Church will participate with this coalition in seeking its passage. Local Church leaders will provide information about how you may become involved in this important cause.
We ask that you do all you can to support the proposed constitutional amendment by donating of your means and time to assure that marriage in California is legally defined as being between a man and a woman. Our best efforts are required to preserve the sacred institution of marriage.