Hello, and thank for seeking technical assistance for your Mac .I am Sr. Mac Support Specialist, TD at your service.
• In order to burn an iPhoto Slide show with iTunes in the background, you would need to have iDVD
All you have to do is take your iPhoto slideshow and make sure it is in an Album.
• To make an Album in iPhoto, simple click on File>New Album
• Name the New Album
• Now with the New Album selected, click from the iPhoto Menu bar on the Share tab
• Select "Send to iDVD" from the menu.
**Allow this some time, as iPhoto, will be transferring your pictures into a new iDVD project.
From here click this link to follow the 3 min tutorial on how to compose your iPhoto/iDVD project
This Video tutorial for iDVD (making a project) is a fantastic, step-by-step process to allow you to be able to add your iPhoto slideshow to a project and add the music from your itunes library to the iDVD project.
(Click the link below. If the link does not open, simply copy the link and paste it in the address bar of your web browser -Safari, Firefox, etc.)
I hope this helps, please let me know if I can be of further assistance.
Thanks, I await your response.