You can invoke the Order Management Integration Layer in either of two ways: through APEX code or through a REST API call.
Invoking Using APEX
Use the Apex global class to invoke Order Management Integration Layer:
vlocity_cmt.OdinService.notify(List<Object> notificationList)
Invoking Using REST API
REST Endpoint to invoke Order Management Integration Layer for OM+ and other third-party order management systems
POST
/odin/v1/notifications