saminanafees:
We are not a letter-writing service, but we can give you constructive feedback on a draft that you would write and post here.
Remember that you have to impress the admissions committee with your letter. It should be succinct, polite, professional and direct. If it has spelling and grammatical errors, such as in your posting, it would not be well received.
You have to introduce yourself, your background, interests and qualifications, goals for the future, why you have selected the school, and the mutual benefits that would accrue if you would be accepted.
Please read THIS