I have one small minor issue with java script/Jquery..I

am making my own JQuery Ajax Chatbox I have got it to stream the data real time, Now I need help in

getting it to submit into the database without refreshing the whole page, After it submits the text field will be blank again.*Im fairly new to Jquery (only a few days) after learning PHP.
Heres the zip to upload locally or in your server.*

http://phpaddict.net16.net/ajax.zip

Once the user hits enter It should submit.
Hope something can add this in for so I can study it/learn.*Thanks.