If God knows what my wants and needs are then why do I need to pray? If  He knows why would I need to ask Him?
These are some really good questions. There could be a lot of answers to them but the most important and simpliest answers are because its a commandment and because of  faith. "And again, I command thee that thou shalt ^apray ^bvocally as well as in thy heart; yea, before the world as well as in secret, in public as well as in private" (D&C 19:28).
Christ is our perfect example and even he, who had the ability to see his Father at any time, even he prayed to our Father. "And when he had said these words, he himself also ^aknelt upon the earth; and behold he ^bprayed unto the Father, and the things which he prayed cannot be written, and the multitude did bear record who heard him" (3 Nephi 17:15). Our Savior who in just a few short hours would be in the presence of our Father knelt down in humble adoration and prayed to his Father to talk to Him and to pray for the multitude.
I am so grateful for the Savior and his example that I have to follow. I have previously written a post on pray. Pray is amazing, it is simple, and it is more powerful than we can comprehend! I love it!

The Power of Prayer

Though most of us have heard about prayer do we know: What the purpose of prayer is? How to pray? or How to receive answers to those prayers?

Hopefully this will help answer those questions. Remember prayer is simple-just a child talking to his/her father- and yet it is so powerful.

What is the purpose of prayer?/What is prayer?

"Prayer is a two-way communication between God and man."

"No on can know of spiritual truths without prayer."

Prayer shows our faith, obedience, and use of our agency (right to choose). When we pray we are acting and not being acted upon.

How do I pray?

1. Address our Heavenly Father ("Our Father in Heaven,...")
2. Express the feelings of your heart (gratitude, questions, requests to confirm that the Book of Mormon is true, and so on).
3. Close ("In the name of Jesus Christ, amen").

"Don’t worry about your clumsily expressed feelings. Just talk to your Father. He hears every prayer and answers it in His way" (Learning to Recognize Answers to Prayer).

Answers to Prayers

It is important to know that we are each entitled to receive personal revelation which comes through sincere prayer. In the Doctrine and Covenants the Lord tells us, "...I will answer you in your mind and in your heart, by the Holy Ghost..." (D&C 8:2). Though He will always answer in some way or another "it is a mistake to assume that every prayer we offer will be answered immediately. Some prayers require considerable effort on our part. True, sometimes impressions come when we have not specifically sought them. They generally concern something we need to know and are not otherwise able to find out" (Learning to Recognize Answers to Prayer).

"He is our perfect Father. He loves us beyond our capacity to understand. He knows what is best for us. He sees the end from the beginning. He wants us to act to gain needed experience:

When He answers yes, it is to give us confidence.

When He answers no, it is to prevent error.

When He withholds an answer, it is to have us grow through faith in Him, obedience to His commandments, and a willingness to act on truth. We are expected to assume accountability by acting on a decision that is consistent with His teachings without prior confirmation. We are not to sit passively waiting or to murmur because the Lord has not spoken. We are to act" (Learning to Recognize Answers to Prayer).

The Lord hears our prayers and He will ever answer. I know this to be true. I am so grateful for the amazing gift of prayer we have been given so that we can personally receive answers and revelation from our Father in Heaven. I know my Father loves me beyond comprehension and I am grateful for that knowledge and the peace and joy it brings to my heart. I say these things in the name of our elder brother and loving Savior, even Jesus Christ, amen.

I Know.

I know that The Church of Jesus Christ of Latter-Day Saints is the one and only true church on the earth today (Ephesians 4:5). I know that The Book of Mormon is the word of God, as is the Bible and together they teach us the fulness of the Gospel of Jesus Christ. I know that through the prophet Joseph Smith the fulness of the gospel has once again been restored to the earth. I know that I can live with my family and my Heavenly Father for all eternity if I remain faithful and endure to the end. I know. You can know these things for yourself if you follow the prophet Moroni's exhortation "...I would exhort you that ye would ask God, the Eternal Father, in the name of Christ, if these things are not true; and if ye shall ask with a sincere heart, with real intent, having faith in christ, he will manifest the truth of it unto you, by the power of the Holy Ghost. And by the power of the Holy chost ye may know the truth of all things" (Moroni 10:4-5). The key to this is having 'a sincere heart' and 'real intent', meaning you truly want to find the truth and fully intend to act on whatever answer you recieve. Faith is a principle of action. You must be willing to act before you can recieve. If you want to read more of my testimony in my Savior Jesus Christ and why I am a member of The Church of Jesus Christ of Latter-Day Saints look up my profile on mormon.org
The Atonement is real, He lives. I am a daughter of God who loves and knows me personally. I am a Mormon.
In the name of our Savior Jesus Christ, Amen.

~Faith~

"Be aware that faith is not a free gift given without thought, desire or effort. It does not come as the dew falls from heaven. The Savior said, 'Come unto me' (Matthew 11:28) and 'knock, and it shall be [given] you' (Matthew 7:7) . These are action verbs- come, knock. They are choices. So I say choose faith. Choose faith over doubt, choose faith over fear, choose faith over the unknown and the unseen, and choose faith over pessimism." -Richard Edgley Oct. 2010

Faith is also a principle of action...choose faith.

http://lds.org/general-conference/2010/10/faith-the-choice-is-yours?lang=eng