Pause for "x" seconds before playing next frame?

I know there is a way but i haven’t figured out how to do this yet… i have three different images and i want them to play for 3 seconds each without having to drag out the timeline. basically it is a slide show. what is the actionscript for this? a few people gave me different formulas, but it stops the movie after the 3 seconds. i’d appreciate any help! thanks.