Read the update notes and check on about the DLC, there's really too much to type it all in one sitting. The best advice I can give you is to set more time for DCUO and see for yourself with a friend who has a mic to fill you in and run content with you. I forgot when Battle for Earth came out but I think you missed The Last Laugh, Hand of Fate, and now we're on Home Turf. Read up on those and you'll get the picture.