How to become an IATA Agent

First, you need to ensure that you meet the local criteria as specified in the 'Travel Agent Handbook'.
Download and complete the 'Application Form'
Pay the accreditation fee as specified in the 'Application Guide'
Send your 'Application Form' to your Accreditation office as specified in the 'Application Guide'
All the documents and forms applicable to your country are available below.

In order to become an IATA Accreditated Agent, you need to understand the IATA Agency Rules (IATA Passenger Resolutions)

The Travel Industry Designator Service, or Non-Ticketing Programme (USA only) is what you need.