I'm an independent freelancer who made less than 10,000k in 2013. This is the first year I've done this full-time and was unaware that I was supposed to pay taxes quarterly (since I received direct checks, etc.)

I've estimated my total income and it comes to less than 10,000k, so I believe I don't have to file taxes. However, I am concerned that I didn't pay quarterly (I had no knowledge of this until recently).

What steps should I take?