Thumbnail slideshow with if statements

1

ok i have a slideshow im workin on which operates by clicking on 10 small thumbnail buttons along the bottom of the stage that trigger a large corresponding picture to appear in the main stage area. i have all of the pics set up as movie clips and am using tell target actions from each button thumbnail to trigger each picture to appear. the problem is, you click one thumbnail, and the picture appears, you click another thumbnail, and the next picture appears but overlaps the first pic. what type of if statement do i need so that everytime you click a new thumbnail, the previous pictures dissappear and only the thumbnails pic appears?