Web Service and Ajax

 Hi,
I want to use web service and page method for web application.
Now it consists of Dropdownlist,textbox and a button.The dropdownlist has item called "Add New" on which textbox which is not visible intially is made visible to add new item in the dropdownlist on blur event of textbox.and when button is clicked all items, added by using blur event must get added to database.
Now how to do this ?I am getting confused.If anyone can provide me the code.or suggest changes in my code to acheive this...

 
Code of Mine:-
JavaScript:
    <script language="javascript" type="text/javascript">
    MultiArray = new Array(5);
    var cnt = 0;
 function CallMe(src)
 { 
   MultiArray [cnt] = new Array(2);
   MultiArray[cnt][0] = document.getElementById(src).value;
   var value = ...