The first-person point of view engages readers personally, for the deepest feelings of joy and terror. It uses the pronouns I, me, my, we, and our to describe the main character’s world, his thoughts and feelings, how he views obstacles and threats, what he does to achieve his goals.
A ship’s captain, facing disaster on the open seas, might describe his plight this way:
As the wave crashed over the railing, I locked my arms around the mast post and cried for my men to hang on.
When writing in first-person intimate, limit your descriptions to what your main character can sense at the moment. Standing on the ship deck, you might speculate on what your men are doing down below, praying, but you can’t reveal exactly what they are saying when you’re not there to hear the words. If you write something like I never saw the land beyond the huge waves, you’ve shifted to the role of a reporter, and readers have been yanked from experiencing the disaster and fearing for the life of his men.
Since you know so much about the story, a wealth of information that your main character cannot see, you face a tough challenge not to drift into an omniscient, telling perspective.