If in a dream you remember any episodes from the past, then you should understand such dream as reflection of reality in your subconsciousness. If reminiscence causes in you disturbing feeling, then, maybe, you should think whether everything was made up to the end. If the past is associated with something pleasant, then just be glad to the fact that life after all is fine.
Be sure and keep any other thoughts out of your mind before drifting to sleep as a cluttered mind can decrease the chances that you will remember your dreams upon waking. Also, focusing on remembering your dreams upon waking in the morning is another very important thing. This sounds very easy, but is often hard for some to do. Interpret a dream by "dictionary dream of interpretation"
When you very first wake up, simply think about your dreams. Don't allow your mind to drift off to other things, just lay there and think about the things you dreamt about the night before - dictionary dream meaning.