Automatically changing text and graphics

I am building a site for a local talk radio station. They are going to have their radio stream live on their site. What I need is an area on the site (about 350px x 350px, this may change) that will automatically change the text and graphics to show who is talking now and who will be up next. It will have to change about every half hour. I am hoping that this can be done simply with JavaScript or PHP because that is all I know a little about. This also needs to be very simple because I will be showing my client how to edit it and they will be the ones to change the content (it will be different each day, and they have no programming experience).