About sharing internet with my friends

Since you offer no information, it is dificult to say. However, Personal Hotspot is controlled by your carrier. You must have permission from your carrier to use it. Once you turn it on, you can offer it to be open to others, once you have provided them with your password. See this for using Personal Hotspot, and the second link for troubleshooting problems. How to set up a Personal Hotspot on your iPhone or iPad - Apple Support and If Personal Hotspot is not working on your iPhone or iPad (Wi-Fi + Cellular) - Apple Support