I thought I didn't have to do taxes because I've been living and working in china since march 2012.

But I heard on the radio as a US citizen I have to fill out something no matter where I live.

I went on the IRS and I see I can fill out forms

A 2555 right?
Is that the only thing I fill out?

I earned about 15,000 USD April 2012-april 2013. I am not sure, I was paid cash and I am not the most organized person to keep track.

Not sure what to do at this point.

You need to file Forms 1040 and 2555. You will owe zero taxes.

If you need professional help, email me at the email address in my profile (if you cannot see me email address below).