How to change picture each time my web page loads?

I want to know how an image can change on my homepage, you know...like showing different christmas pictures when my web page loads on a users computer. I want them to see a different picture each time! Does this kind of design involve DHTML?How to change picture each time my web page loads?
store all image in array and display one file at page load by select random no and image with respect to that no.How to change picture each time my web page loads?
There are many ways to do this. You can give user a cookie that records the images they have seen to avoid repeats. Or, simpler, write some code to give a new image each day. Probably easiest done in something like PHP.