You have provided textual evidence for your first point, now provide it for your second and third points. Then conclude your analysis by briefly summarizing your main points and reiterate that it is conclusively a formal essay.
The poet, Yeats, is describing the daily routing of an old mother. He presents his ideas in a poem describing how she completes those activities. He is descring the old woman as hardworking and tired, and he presents these ideas in the last line, where it says that she must work because she is old and the seed of the fire (a lantern most likely representing her life or her day) gets feeble and cold (it ends). In essence, the author describes the old woman as harworking and tired, and at the end of the day, the "fire," or the Sun, grows feeble and cold, signifying that the day is ending and the cycle will begin again tomorrow.