Bootable DVD doesn't load up windows setup

[MartianGeneral]

Hello, I want to install windows 8.1 on my pc which has windows 8 installed. I created a bootable DVD using 'Win7 USB/DVD Download Tool' and it showed a success message at the end.
When I shut down my PC and then restart it to enter BIOS to choose boot order, I choose CD/DVD option but the computer restarts and then directly goes to the screen where I normally choose if I want to start up win7 or win8.
I tried bootable USB but that doesn't even show up in the bios boot order list.
Please help me install this.
Thank you for your time and pardon me if this has been posted in the wrong section.

 

[06yfz450ridr]

if you already have windows 8 go to the windows store on the metro side and download windows 8.1, its basically just an update

 

[alexoiu]

Hi, Try Rufus for making a bootable USB and copy the Windows files on it.
Connect the USB to a 3.0 port.
At restart, press F8 or F12 or F11 (depending on the board) and select the removable from the boot menu.