Can Someone Help Me Please???

Hello, I am trying to do a clean install of windows but I lost the Windows 7 Disk, I found the product key with speccy but I still need to have a bootable windows 7 disk. I have downloaded Windows 7 Home Premium 64-bit from this website.

http://www.mydigitallife.info/wind [...] e-premium/

But I am confused on what I am supposed to do next, Can someone please tell me? The page where I downloaded it from says that I need to go to this page to make it bootable.

http://www.mydigitallife.info/how- [...] box-files/

But that is for making an ISO image but the Windows 7 file that I downloaded says that it is already an ISO and the site says that you can directly download the ISO image from "this link" but it just takes me back to the place where I downloaded the file in the fist place, someone please help me! I have never done this before and I really need some help.
-THANKS!