Before you use the API please ensure that you have access to some organisation.
To issue a new token please navigate to your profile, then "Access tokens" section and press "Issue token" button.
After the token is created you can use it to access the API:
curl http://{domain_name}/api/documents/v0/CertificatesOfOrigin/ -H "Authorization: Token {your token here}"
This is a simple REST API - please use your favourite client library to work with it.