The first thing you need to do is read the poem, and then read it again highlighting anything that sticks out to you. You next need to think about what the theme of the poem might be. Once you have decided on the theme you will discuss, you should choose one quotation which supports your theme, and analyse this quotation. Remember to identify a technique and explain the effect. The more you can say about a small amount is one of the things for AO2, so even if you don't understand the poem fully, if you can explain the effect of a small section you will already be gaining marks.