Sending messages to Connectors and Webhooks - Teams
To send a message through your Office 365 Connector or incoming webhook, you post a JSON payload to the webhook URL. Typically this payload will be in the form of an Office 365 Connector Card. You can also use this JSON to create cards containing rich inputs, such as text entry, multi-select, or picking a date and time.
https://docs.microsoft.com/en-us/microsoftteams/platform/webhooks-and-connectors/how-to/connectors-using
