How to add item to two or more textbox via javascript(Onlick)

Greetings Guys,
As a novice to JavaScript I am unaware of how to implement a program in which a smiley or any other text can be added to two more more text boxes when the image is clicked. Any help would be appreciated. . 
<img src="Smiley.gif" alt="Smiley" onclick="Addthis(Smiley)"/>
 <script type="text/javascript" >
function Addthis(text)


{


    if (document.getElementById('textbox1').focus == true) 


    {


    alert("textbox1"); 


    }


    else if (document.getElementById ('textbox2').focus == true)


    {


    alert("textbox2" ...