How must I do to turn 'personal hotspot' on iPhone 5?

In Settings I can't choose personal hotspot. The icon is shaded (on pic). How must I do to turn on personal hotspot?
I got iOS 7.1.1
How must I do to turn personal hotspot on iPhone 5 - 1

You have to turn your cellular on in order to turn on the hot spot.

Why is your CELLULAR off? You can't turn your phone into a Wi-Fi hotspot if you are only connected to Wi-Fi.

If there's already Wi-Fi in the area, why would you need to turn your PHONE into a hotspot?

Do you have a number I can call