How to boot Kali Linux:

After creating The bootable USB/DVD as i have given the tutorial above place the DVD in DVD-ROm or plug in the USB then shutdown your PC.After your PC is shutdown turn it on and go in your boot menu by pressing the boot menu key on the right time.for eg to enter in the boot menu i need to press the F12 key when Toshiba sign comes on my Laptop.
The boot many may look like:

Boot menu

Select USB if u have plugged in USB or Select CD/DVD if you have bootable DVD.Now,after selecting DVD/USB Kali will boot up and this screen will come up:

Kali boot menu

Now,select the first option i.e Live (amd 64) now it will load some necessary files but it won't take much of your time.

Necessary files loading

After this you will see Kali's desktop now u are in the world of hacking.