And is linked from the Call for Papers. (The url for the server is http://focs2014.cs.princeton.edu , though please do read the call for paper, and the advice linked below, before submitting.)
The deadline is 4:30pm Eastern Time on Wednesday, April 2nd, but I’d suggest you try to submit the day before to allow extra time for fixing all those typos and implementing all those suggestions that usually come to you just as you press the “submit” button. (Not to mention to allow time for computer crashes, network outages, latex bugs, bathroom breaks, and all those other pesky issues that tend to pop up 5 minutes before the deadline.) While you’re at it, I recommend you post the paper also on the arXiv, ECCC, or ePrint, so other people can benefit from your work.
Now go and prove that missing lemma – I’m looking forward to reading your submissions!