Why cann't I boot from CD?

[Stephen]

I had downloaded the iso file, and then I put it into the virtual CD, thus I can get all the files of the iso file, then I burned all the virtual CD to a CD ,but I cann't boot from it?

Is the right way of burning CD is to burn the iso file to CD directly withouting unzipping it?

In addition to the suggestions above you have to use the option in your burning program (whatever it may be called) to create a bootable CD from an ISO image.