how do I change a gui texture at certain intervals?

I need a loading screen for my game, as the level loads. The idea is that I have a scene that opens (a loading scene, you could call it), and that that scene plays a slideshow as the level loads. I wrote a script that loads the main scene in the background, as the current scene (the loading scene) plays the slideshow. I am having trouble with a script that will change the image of a gui texture every X seconds. I have about 10 pictures I want to rotate through, on a loop, with about half a second in between each picture. I tried setting each picture as a var, but that did not work. Can anyone help?