The church issued "The Family: A Proclaimation to the world" in 2000 and it states that a family is to consist of one man and one woman

The Church publishes a pamphlet called,"God Loveth His Children", which addresses the subject

In a interview titled Same Gender Attraction Elder Oaks And Elder Wickman address this question this quote is the last paragraph of the twelve page interview, It summarizes the churches views on this topic. 
Elder Oaks 
"God loves all of His children. He has provided a plan for His children to enjoy  
the choicest blessings that He has to offer in eternity. Those choicest blessings are associated with marriage between a man and a woman by appropriate priesthood authority to bring together a family unit for creation and happiness in this life and in the life to come.  
We urge persons with same-gender attractions to control those and to refrain from acting upon them, which is a sin, just as we urge persons with heterosexual attractions to refrain from acting upon them until they have the opportunity for a marriage recognized by God as well as by the law of the land. That is the way to happiness and eternal life. God has given us no commandment that He will not give us the strength and power to observe. That is the Plan of Salvation for His children, and it is our duty to proclaim that plan, to teach its truth, and to praise God for the mission of His Son Jesus Christ. It is Christ’s atonement that makes it possible for us to be forgiven of our sins and His resurrection that gives us the assurance of immortality and the life to come. It is that life to come that orients our views in mortality and reinforces our determination to live the laws of God so that we can qualify for His blessings in immortality."Same Gender AttractionSame Gender Attractionnull

The Family: A Proclaimation to the world, says marriage is between a man and a woman. 
Homosexuality is out of the picture. In the book "True to the Faith" it says (under the topic chastity) "If you find yourself struggling with sexual temptations, including feelings of same-gender attraction, do not give in to those temptations. Be assured that you can choose to avoid such behavior. You can receive the Lord's help as you pray for strength and work to overcome the problem. As part of this process, you should seek counsel from you bishop or branch president. He will help you." 
Homosexuality is not the way God wants us to live. If one struggles with it, no matter how difficult, he or she can receive help. We all have agency, and one does not have to give into those urges. 
It's also important that we as members do not judge others.

We believe that homosexual actions and thoughts is a sin. Because it is a sin, that means it is a choice. 
 
The church's stance is not all negative, however. There are groups like Evergreen International that members with homosexual tendencies can join to help them cope and overcome their problems.

i see no problem in loving whomever you want to love, but i dont know if you should marry them. 
 
im trying to convert to mormonism. 
so now my ideas are being conflicted

I've never heard an LDS authority say that actual same-gender attraction is a choice. Maybe it is, maybe it isn't, I don't know. 
 
What I do know, however, is that everyone has the choice to choose whether or not to act on those attractions. The church teaches that individuals should not. It might be a serious challenge for them, but it's not impossible. Everyone can overcome temptation. 
 
We believe that marriage is between a man and a woman not because we want to discriminate, but because we believe that it is part of God's plan in the afterlife and in the eternal perspective, and marriage between a man and woman is a very sacred part of that plan.

rachel I understand where you are coming from, I felt the exact same way until a prayed. You must remmeber that the prophet's speak the word of God, not their own personal beleifs. If you are struggling I urge you to pray to him to know the truth for yourself, its helped me with these sort of standards more times than I could count!

The Church does not accept homosexual acts. Someone cannot be an active member if the are violation the law of Chastity (premarital sex) and the Church does not recognize same sex marriage. So even if a homosexual couple was legally married they are still violating the law of chastity in the eyes of the Church.  
 
 
The Church is set in stone on this because it is the commandment of God recorded thought the Scriptures.  
 
Some one can be attracted to the same sex and openly serve and participate in the Church. They must be obeying the law of chastity though.  
 
Same sex attraction is not a sin, and the Church does not endorse, condone, or allow discrimination, violence, or rejection of any person based on there sexual orientation.  
 
We all have the right to choose how to live our lives. The Church does stands against same sex marriage on the grounds that marriage is a sacred ordinance of God between a man and a women that cannot be changed altered. But we accept and love all men and women regardless of there orientation, race, creed, religion, ect just like Christ love everyone!

I am pretty sure that the mormon church lobbies activly against gay marrage laws.