Just to be sure that there is no misunderstanding, for the benefit of VERY new users:

If you burn the ISO file as an ordinary "data file," then it is not bootable. As far as your computer is concerned, it is simply some sort of file on the CD.

You need to burn the ISO file as an "ISO image," which actually unpacks it and arranges it on the CD (or something like that), rather like unzipping a zip file. When you explore the CD, you will see a file structure, not just one huge file.

Some CD burners don't include the option to burn an iso image, or maybe that option wasn't selected when burning. My own computer came with 2 burners, niether of which has the option.

If in doubt, search the Internet for Alex Feinman's "ISO Recorder," which provides a right-click context menu specifically for burning an iso image.

That doesn't sound like the issue raised in the above forum discussion, but I image some new users will find their way here, with the problem I just described.