Hi im developing an app, i want to generate an operator message like this. How to do that ?

Hey Rajabdeen, what is it exactly you are trying to do?To assign a conversation and create a note (Inbox features) you will have to use Intercom's API. Here is the documentation on how to assign a conversation, and to add a note to a conversation you will hate to create a reply message with message_type=note as documented here.