I would suggest that you begin your analysis by determining who the speaker/writer is. What is their background, motivation for saying this? Then look at the context under which the quote was given. Who is the audience that is being addressed? And finally, what was the purpose of the quote? Was the author trying to convince someone of the importance of nationalism, speaking out against it?
You also need to know what nationalism is: extreme patriotism for one's country. Knowing that should help you pick out other key terms/concepts in the quote. If you are unsure if a term is related, such as self-determination, you will want to define them as you go through the quotation.