Select Client > New to create a new client
For more information about How to Create a New Client
http://help.rentlysoft.com/en/articles/5313631-how-to-create-new-clients
Select "Is Agency" to enable to link to a Commercial Agreement.
Complete with its IATA Code
In case you need to make a Commercial Agreement with a Hotel, it is necessary to select both : " Is Agency" and "Is Hotel" due to that Commercial Agreements are only linked to Agencies.
Remember to always save changes