Prepare for IB internship - High School Student attending Stanford

Hi all, 

I am currently a senior in high school and will be attending Stanford this fall as an economics major. I was able to secure an internship this summer with a regional investment bank and will be working with the mergers and acquisitions team. My question is, how can I prepare for this internship? I know nothing about finance, excel, mergers and acquisitions, or investment banking. I see that there are investment banking modeling courses, but I don't believe that I am qualified to complete those as of know as I know nothing about finance. Does anyone have a suggestion for an intro course I can take that would prep me for this internship? I don't have much going on, so it'd be great to read up on some basics or develop some modeling skills. Thanks for all the help!