Subheads are basically the small titles that are smaller than the original title. Sequence is like First, Second, and etc. You basically have to explain why do subheads support the sequence of your text, passage, and etc. Hope that explains to you!
<h2>Answer:</h2><h3><em>The poem 'Rain on the Roof' talks about the poet's varied reactions to the sound of raindrops falling on the roof of his house. He says that the raindrops at night are like tears shed by the sad, dark night. ... He says that the sound of rain drops helps him fall asleep and gives him sweet dreams</em><em>.</em></h3>