You can't add a local bank account / debit card in your country. You can only link a credit card.
Also the option to receive Paypal payments is sadly not available in Nigeria. You can only send payments for purchases funded by your (confirmed) credit card.
Paypal varies a lot country to country and can only offer the services that the banks / governments of that country allow it to offer. There are quite a few countries unable to receive Paypal payments.
