Adding a textbox to an image slideshow Forums: Javascript

Hi. I am using Dreamweaver CS6 for my website and now I have a very basic question: how do I replace an image over text (a text box?) in a slideshow using javascript? Meaning, I have a gallery of thumbs and when i click on the last thumb insteat of an image, a text box should appear. How can I do it?

<a href="javascript:;" onclick="MM_swapImage('main','','images/S_07.jpg',1)"><img src="images/t_07.jpg" alt="t_07" name="t7" width="84" height="56" id="t6" border="0" /> </a>