With regard to writing a compare/contrast essay on Roethke's "My Papa's Waltz" and Hayden's "Those Winter Sundays," I would come up first with a plan on how to structure your paper, and decide on what aspects of the poems are the same, and others that are very different. Start with your thesis statement in your introductory paragraph.
For the sake of organization, I would then delegate the next paragraph (the first body paragraph after your introduction) to provide—let's say—the "comparison," the things the two poems have in common. You should start this paragraph with a topic sentence, so the reader knows what the paragraph is about. When you make your general statements about the poem, then you must support them with specific details from each poem to "prove" your point.
The next body paragraph would probably then be your "contrasting" paragraph, using the same structure as outlined for the "comparison" paragraph, supporting general statements with specific details.
The next body paragraph would provide your response to the two poems, which are decidedly different, especially in their tone and mood.
Your conclusion (the final paragraph) should reflect your closing thought: do not repeat information you have already covered, but make a statement perhaps about the distance that separates the mind of a child from the larger-than-life actions of an adult: this can be where you make your "judgment" call, closing your "discussion" with one or two sentences that bring the paper to a close.
Specifically, I would read both poems several times and circle or highlight the things the "stories" have in common. For example, there is a father in both, and each man does physical labor. There is also a child in each poem. There is also a great many sensory details: the scraping of the ear on a belt buckle, and the smell of whiskey; and, the "cold splintering, breaking."
I would also be ready to make notes in the margin of your poems. The mood and tone are very different in each poem. (The mood is how you feel reading the poem; the tone is how the author feels in writing the poem. "Mood" is generally easier to describe.) "My Papa's Waltz," by Theodore Roetke is a favorite poem because it seems to be about a romp around the kitchen before bedtime with dad.
Your interpretation is essential here because you are responding personally to this writing. Your ideas and feelings are important. Poetry does not have right and wrong answers...unless you are completely off and believe, for instance, that there are aliens in the poems somewhere. As long as you can support your ideas/feelings with specifics from the poem, you are as correct as anyone else in your interpretation.
The second poem, "Those Winter Sundays," by Robert Hayden, has a very different mood. The youngster in the poem has a different relationship with his father. Note how they interact, the child's stilted communication with his father, and what his father is doing on this cold Sunday morning. There is no laughter or dancing, and the poem provides a stark statement about the relationship between father and child in the poem. The lines at the end might even help you to find your conclusion for your final paragraph.
In many ways, this is a "process paper" that usually follows the same pattern every time you write a compare/contrast paper. (See link above.) I hope this information in structuring the paper, as well as elements of the poems to compare and contrast, are of some help.