Now we're ready to fire up Kali. Insert your Kali USB drive into your machine and power it up. In the beginning of the boot process you will be given the ability to manually select a boot drive. The specific keystroke will vary depending on the type and make of your machine. By whatever process your machine uses you will be given a menu of the available drives to boot from. Pick the USB drive and continue. When the system boots, you will be presented with a screen asking for your passphrase. This is the passphrase you chose earlier during the installation. This is not the root login password. Enter the passphrase and hit the Enter key.
This will start the actual boot process of the system from the now ...