Hi for the first day or so you could focus on yourself and have the class learn about you as suggested before. Even though they are adults they like to play games often so class isn't boring. For other class days you might want to try
Breaking News English ESL Lesson Plans for Current Events they have current events and appropriate advanced and beginning lessons for the current events on the website. You can also try the Korea Times, they have a Dear Abby section with Korean vocab. to help students with some of the more difficult or metaphorical English words in the column. Hope this helps.
Best Wishes,
Gigi