" And now I, Nephi, do not make a full account of the things which my father hath written, for he hath written many things which he saw in visions and in dreams; and he also hath written many things which he prophesied and spake unto his children, of which I shall not make a full account."
The entirety of the vision would have been too sacred to share. By the spirit are parts allowed to be written. When the world is ready to receive such things will they be made known through a prophet of the Lord.
Lehi wrote down the things of which he saw, which was probably in the 116 pages that were lost in the time of Joseph Smith. By the word of the Lord those pagers were not re-translated, instead the book of Nephi held the words the Lord allowed to be translated.
Lehi saw and recorded the things he saw in visions much like many other prophets. For example Daniel, Joseph of Egypt and many more did this. The prophesies of the prophets are recorded, much like in the past. Here Lehi did the same and Nephi also recorded the part he felt was necessary as the spirit directed.