This Surah is named Al-Fatihah because of its subject-matter. Fatihah is that which opens a subject or a book or any other thing. In other words, Al-Fatihah is a sort of preface.
This Surah is in fact a prayer which Allah has taught to all those who want to make a study of His book. It has been placed at the very beginning of the book to teach this lesson to the reader: if you sincerely want to benefit from the Quran, you should offer this prayer to the Lord of the Universe.
This preface is meant to create a strong desire in the heart of the reader to seek guidance from the Lord of the Universe, Who alone can grant it. Thus Al-Fatihah indirectly teaches that the best thing for a man is to pray for guidance to the straight path, to study the Quran with the mental attitude of a seeker- after-truth and to recognize the fact that the Lord of the Universe is the source of all knowledge. He should, therefore, begin the study of the Quran with a prayer to him for guidance.