If this is the first time you have used a Personal Hotspot on your phone, you will first need to activate it by tapping 'General', 'Cellular', 'Personal Hotspot' and switching it to 'ON'. Next time, the 'Personal Hotspot' option will be available in your 'Settings' menu.
In addition, if you're connecting a computer that has previously used an iOS device Hotspot, you'll first need to remove the old saved network details from your computer.
You can do this through the 'Network and Sharing Center' of your computer, by removing the old Hotspot in the 'Manage Wireless Networks' section.
From the home screen, select 'Settings'.
Select 'Personal Hotspot'.
Set your Personal Hotspot to 'On'.
Once it's active, you can choose a password for your Personal Hotspot by selecting 'Wi-Fi Password'. We highly recommend you set-up a password to protect your Personal Hotspot from unauthorised access.
Pick a password that is a minimum of 8 characters, then select 'Done'.
To deactivate your personal Wi-Fi Hotspot, follow Step 1 to 3 above, changing the setting to 'Off'.