How do I put a hotspot on my iPhone

Hotspot is a feature or option that is provided by your carrier. Not all carriers offer this option.

On your phone.....Tap Settings > Cellular > Personal Hotspot

If you do not see a Hotspot setting, then you will need to check with your carrier to see if they offer this option.

That's a feature you need to pay for through your carrier. Contact them to see what would be required for you to have Hotspot service on your iPhone. It usually requires an unlimited data plan, so there may be added cost if you don't have one currently.