Death of a Salesman is a very popular work; I would suggest just typing the name in an onine search engine; you could perhaps also search for the title of the text along with "analysis". This could get you started on secondary sources. As far as the type of analysis, what does your assignment require? Do you have to use a specific analytical method, or is that up to you? If it is left up to you, I would also pick a critical analysis theory to apply to the work. You can research those by searching onine for them also.
I hope this helps you get started!