OK, but what is your actual question?! I assume you already have a topic/subject for your essay, so you need to find a suitable Shakespearean quote which will make sense to the topic. Once you have done that, I would suggest putting the quote in quotation marks, or in italics as your first sentence so that it's clear it's a quote.
You also need to make sure that it's relevant and that you can make it clear why it's there.
Depending on the type of essay, you may also need to remember to acknowledge the quote at the end (say who wrote it, and perhaps which play it's from).