The first step in writing an essay about a poet is to select which poet and what it is that you want to say about this person. Perhaps you want to write about what his/her life was like and how it influenced his poetry, what contributions were made to poetry, or which theme was the common link in all his/her poems. Once you know what you want to say, the introduction will give the thesis statement which explains what you want to prove and introduce the main ideas which will be used to prove your thesis. For example, if you were to choose Ben Jonson who lived from 1572-1637 and was something of a rebel, you might discuss his beliefs in life, use his poem "To John Donne" to illustrate the qualities or beliefs which were important to him, and then use his plays or general body of poems to show his contributions. Remember that you must introduce the ideas you will be proving about Jonson in the introduction, prove your ideas in the body, and then conclude your paper with a restatement of your thesis. Using Ben Jonson is only for an example; many modern British poets may be your preference.
Thank you very much Mizzwillie.