You may need to start by determining what you want or need to include in your paper. The specific points you plan to make may shape your introduction.
You could focus on the life cut short by the buzz saw, discussing the tragedy of the accident, the impersonal and unfeeling reactions of the others, the hardship of "doing a man's work, though a child at heart" using the power equipment at the end of the day when he was already tired.
You could contrast the tranquility of the setting - mountains rising in the distance at sunset and "sweet-scented" sawdust in the breeze - with the image of the severed hand from which "the life was spilling...all was spoiled."
You could consider the value of a human life. How did the boy's family members feel? "Since they were not the one dead, turned to their affairs" - what does that reaction say about them, or about any human reaction to grief? Frost endured many tragic deaths in his own family. Does that history figure into the writing of this poem?