Follow the below guides to activate a wireless hotspot on your mobile device.
Note: This service is not available on all mobile devices or plans and is only available for cellular-enabled devices. Please contact your cellular service provider to find out if this service is available to you.
You can follow this guide provided by Apple for setting up your wireless hotspot on your iOS device.
You can follow this guide from the Android support site for setting up wireless hotspots from your Android device.