Rotate image on slideshow (iMovie) ???

I want to make a slideshow for a wedding I attended. I took pictures and uploaded them onto my iMac. When I dragged the photos onto iMovie to make a slideshow my vertical images are now horizontal.... How do I rotate my images because I am getting very frustrated with this. If it matters, on my iMac when I look at my photos I uploaded from my camera, the image thumbnail makes the photos all look like they are horizontal, but when I click a picture that is suppose to be vertical it shows up vertical... just for some reason the thumbnail is horizontal. I hope I am making sense... can anyone please help me???

Basically I just want to rotate my pictures so they appear vertical like they are suppose to appear.

Oh I also have iDVD so if anyone knows how to do it on that also, that would help, because I tried making the same slideshow on both programs, but this rotating images is really getting to me now.

Thank you