What are some general points of the story that i would need to know to be able to have a conversation about it?

For a general look at the novel, you might want to read through Gradesaver's short summary. I'd also advise you to read through Gradesaver's theme page.

http://www.gradesaver.com/frankenstein/study-guide/summary

http://www.gradesaver.com/frankenstein/study-guide/themes