Hello everyone my name is Boniface from Zambia. How do do I unlock carrier from iPhone 5S

Look here -

How to unlock your iPhone for use with a different carrier - Apple Support

You may want to reconsider your purchase, that phone is extremely outdated, it won't run most of the apps in the App Store or most social media apps. The battery is going to be bad and you can't get a genuine Apple replacement battery.

If it’s carrier locked, it’s due to nonpayment of the device or reported stolen. You should have checked IMEI number before purchasing these phones. As it would have told you it was carrier blocked.

Carrier locked means it's locked to that carrier and you can't use it with a different carrier until the carrier it is locked to unlocks it.

You are thinking of being blacklisted by the carrier.