Loading Random Pics

Newbie question its probably been asked 1000 times but I couldnt find it so:

I want my program to grab a random image from a Pic folder and display it in a Picturebox then I am going to have buttons that will move the selected image into a certain folder then I want my program to load the next image in the Pic Folder I know how to do the buttons and I know how to grab a specific image I cant figure out how to make it load a random image from that folder and then load the next one when that one is gone. Thank You