Read and make notes (particularly questions you may have) ahead of next Thursday's lesson.
We will go through this carefully.
First, you can use the excellent structure I gave you a couple of weeks ago:
Representation theories from Great Baddow High School Media
UPDATE: I HAVE JUST FOUND THIS ONE WHICH IS ALSO VERY HELPFUL:
UPDATE: I HAVE JUST FOUND THIS ONE WHICH IS ALSO VERY HELPFUL: