An ISO image file is an archival format used to create exact copies of a CD or DVD. This unalterable ISO file must already be a snapshot of a bootable disk for you to create a bootable disk from it. This essentially means the ISO file must contain the programs and structure necessary for your computer to boot from it exclusively, absent any operating system. You can easily create this bootable CD or DVD using the free ImgBurn program.
Insert a blank DVD or CD into your drive. The disk chosen should be of the type required by the ISO image file. An easy way to determine this is to look at the ISO file size in Windows Explorer. If the size is less than 700 MB, then you need a CD. If it's more than 700 MB, but less than 4.7 GB, you need a DVD. If it's more than 4.7 GB, you need a double-layer DVD.
Click the "Write image file to disk" button in the selector screen.
Click the folder icon under the "Source" section, locate the ISO file in the navigation window, and double-click it.
Select your CD/DVD drive from the "Destination" drop-down list. If you only have one such drive, it should already be selected.
Click the large bottom button that shows a picture of a CD/DVD. The ISO image will be written to your CD/DVD to create your bootable disk.