Create a .env file with the following values:
API_KEY=<INSERT YOUR KEY HERE>
ISSUER_DID=did:dock:myissuerdid
RECIPIENT_DID=did:key:walletholderrecipient
API_URL=https://api-testnet.dock.io
For some examples you may need to register an issuer DID, view the documentation.
RECIPIENT_DID typically will be a DID from a wallet application