In the poem "There Is No Frigate like a Book", the A - main idea is that books can transport your imagination and soul to all different parts. She conveys this by making an analogy between means of transportation and literature in the poem.
This is a short poem and has nothing to do with B- the life of dickingson, or the C- the poetic structure. The D- word choices she uses are as I mentioned, to compare different transportations: frigates and coursers, to literature.