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 Tunisia. 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.
