You can generate a self-signed certificate if you do not need your certificate to be signed by a CA, or you wish to test your new SSL implementation while the CA is in the process of signing your certificate. This temporary certificate will generate an error in the client browser to the effect that the signing certificate authority is unknown and not trusted.
For creating a self-signed certificate through CLI, execute the following command.
wadm> create-selfsigned-cert --user=admin --port=8989 --password-file=admin.pwd --config=config1 --token=internal --org-unit=org1 --locality=XYZ --state=DEF --validity=10 --org=sun --country=ABC --server-name=serverhost --nickname=cert1
See CLI Reference, create-selfsigned-cert(1).