How do I describe the way a poet tells a narrative?

First of all, it's good to remember that the term narrative means "story" and that you are looking for ways that the poet uses language to describe what is happening. More than that, though, a narrative makes the reader feel empathy or interest for the events that are unfolding and you want to find examples of how the poet does this.

Therefore, you are looking for specific words (adjectives, verbs, adverbs) that describe the events or conversations that make up the narrative and assert what effect they might have on the reader. In the phrase "To boldy go", for example, the adverb "boldly" describes how the journey begins and also makes the reader feel empowered and enthused. As the form is poetry, you are also looking for specific poetic techniques such as line length, punctuation, rhythm and rhyme that heighten the way the reader feels about the story that is being told. Highlighting specific words and connecting them to the poetic techniques you have noticed will provide you with a description of the way a poet tells a specific narrative.