How can I upload this movie from iMovie to a DVD, for goodness sake!?

How can I upload this movie from iMovie to a DVD, for goodness sake!? Okay, so I have a MacBook Pro. I have iMovie, but I don't use the new iMovie, I use the older one. The one with this icon:
http://www.udel.edu/smdc/training/imovie/imovie_icon.png
So, then I transferred the movie to iDVD. And then I put in a DVD-R disk. It would load for like 10 minutes. It would say it is done and spit out the disk, but it would say under the loading bar-4 minutes remaining. So, I kept trying it. It didn't work. So, I went back to iMovie and exported the movie to Quicktime. I then emailed the Quicktime file to my teacher. She has a Dell computer. She got it and tried to open it, but she doesn't have Quicktime on her computer and she would have to buy a 70 dollar software for it, so I said "Could I bring it tomorrow for full credit?". She said that I could. So, I went home and my brother looked at it to see if he could do it. And he said I needed a DVD+R. So, I left to Longs Drugs at like 10pm and it was closed, so I left at 7:30 am [before school] and got the DVD+R disks and I pulled out my laptop and put in the disk. I tried to upload the thing from iDVD again but it just spat it out. =[ Now, I don't know what to do.
 
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