It's not a functioning game? I was clicking the x's and o's for half an hour trying to get them to change!
Well no one here is going to give you code. However we are more than willing to help you when you come across errors and get stuck. Since you know nothing I recommend you learn the following:
Data types, Arrays, Methods, Objects, Swing, Action Listeners
Just a few things to start off. I'd recommend making the game in a console format first so you learn the mechanics then turning it into a GUI format. It won't be much different in GUI but you will have to learn how to add action listeners to buttons and drawing components to your window.