How can I unlock my carrier???

You must contact the carrier the phone is locked to and ask about their unlocking policy. Then→How to unlock your iPhone for use with a different carrier - Apple Support

You don't unlock the carrier. The carrier unlocks your phone. Only your carrier can unlock the phone. You cannot do this.

Contact your carrier and ask them to unlock the SIM card in your phone. Please note that they are likely under no obligation to do this, so you may have to continue to use the cellular service provided by your carrier.