gpg --list-keys
To list defined public keys on the system
gpg --list-secret-keys
To list defined private keys on the system
gpg --import COMPANY.sec
To import private key
gpg --import public_key.asc
To import public key for partner
gpg --encrypt example.txt
To encrypt the file, output as example.pgp
gpg --output example.txt --decrypt example.gpg
To decrypt the file example.pgp, output as example.txt
gpg --edit-key <KEY> trust
or
gpg --edit-key (ID of partner key)
Choose ultimate trust.
To give permission to use pgp keys for every files.
Note: Every user has its own gpg keyring so everyone should import their own keys
Related Source: http://www.spywarewarrior.com/uiuc/gpg/gpg-com-4.htm