How do I use my phone as a hotspot?

@TinanevilleIt's typically under Settings->Data (of some sort, customizations apply).

You want to set a password first though, before you actually enable it, to prevent others from "hopping on", in a variety of ways.

If you can't enable it, it's because you have a plan that doesn't come with it. This includes some of the old Unlimited plans, and around that era, and some others, and the current "Unlimited Choice" plan as well, it's a key differentiation from the "Plus" plan.

If one of these applies, you have to consider switching to another plan, if you want to use the hotspot/tether.