Issue certificates on the blockchain

I am new to blockchain and blockcerts. I am doing in testnet mode (bitcoins). I have copied the sample unsigned certificate from examples folder in cert-issuer to /etc/cert-issuer/data/unsigned_certificates.
I got stuck at running the below command
cert-issuer -c /etc/cert-issuer/conf.ini, getting error
cert-issuer: command not found.
I have gone through a solution, by running the below command (python3 -c conf.ini) , but getting error
Traceback (most recent call last): File “”, line 4, in <module> from cert_core import Chain ModuleNotFoundError: No module named ‘cert_core’.
Can anyone please explain me what these both commands do ?
I have created conf.ini and pk_issuer.txt in the folder path /etc/cert-issuer/. Do I need to run above command in bash? In configuration file can I replace issuing_address directly with generated bitcoin address in the place of issuing_address in conf.ini.

issuing_address =



After running cert-issuer -c /etc/cert-issuer/conf.ini, what is the data generated in pk_issuer.txt file? I am not clear with the concept after issuing certificates to blockchain. Please clearly explain me the steps to follow from here and concept too.