Adding + symol to the movie clip i clicked

Hi Everyone!

            Advance thanks for the help, I am populating the images from the xml file and it is populated as 

a gallery, i done the the roll over and roll out effects by using this keyword, now i want to add a + symbol over the image
when the image is clicked when the user clicks again the images with symbols it should clear the + symbol from the images, This is same concept done in Kaltura, please visit kaltura.com to see this in action.

Regards