Installing Windows 7 in Boot Camp with iso

I have downloaded an .iso file with Windows 7 on but I can't install it in Boot Camp. I've tried several things with no luck.

1. For the first, when I start up Boot Camp assistant I can't choose to "Create a Windows 7 install disk". I only have the two bottom options, the one for downloading support software and the one for installing windows 7. So I can't use my .iso file there.

2. I tried to burn a bootable dvd with the .iso file. I burned it on a Windows PC since my superdrive won't burn on the discs I've got (DVD+R). The disc works properly on the Windows PC but when i mount it in my Macbook I only get a popup that says I've put in a blank disc and some options of what I wan't to do next.

3. I tried to make a bootable flash drive and that pops up in finder, but the Boot Camp assistant won't recognize it and says I have to put in a Windows 7 install disc.

4. I also tried to open the image file in disc utility, but the result is the same as if I'm trying with a flash drive.

I'm out of ideas now so it would be nice if someone else knew any other possibilites to install Windows 7 in Boot Camp.

Or maybe there is an solution for the things I've alleready tried?

I'm using a MacBook Pro late 2008