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.

What is Kali Linux:

Guyz this post will tell u about the Kali linux.I will tell you how to install this software and how to hack.The software name is Kali Linux as the name clearify it is base on Linux debian image.It can be installed on Laptop,Android phone.
First of All you have to download Kali Linux from HERE.You may download it according  to your need like 64 bit or 32 bit, but it should be .iso format if want to create a bootable USB.

How to install Kali linux

After you have downloaded Kali linux I will recommend you to burn it in DVD but you can also install it in USB and you can create a bootable USB.To make a bootable USB you will have to download Rufus(link given in end).You will need at least 4 GB USB to install Kali Linux on it you can also use this software to create boot able DVD.
Link to Rufus.Plug in your USB before running Rufus Warning:all your data will be formatted so please backup your data using Rufus is safe i have tried it myself.
Screen Shots:

Rufus

To select the file u want to burn click the disc icon.It will ask you for the folder navigate the folder in which you have downloaded the kali linux.

Now select Kali Linux and click start it will Format your USB and then it will burn Kali Linux in your USB/DVD and it will become bootable.