1) First, you should choose a trading strategy on the C2 web site and click on the Autotrade button from the top menu.
2) This will bring you to a "Choose a broker" page. You must click on Show all compatible brokers:
3) Then click on TradeBullet at the bottom of the page and then click Next step:
4) Type in your IB account number and click Submit.
5) A page appears where you can make last minute changes such as changing the scaling % (click on 100%), etc.
6) Click on "Turn on Autotrade". You are done on the C2 side of things.
7) Now you must setup TradeBullet. Setup instructions are available at http://www.tradebullet.com/user-guide (see C2 section)