To receive notifications in a private channel, a group, or directly to your own account, you will need to create a Telegram bot. Follow the instructions on creating a Telegram bot on Telegram's Bots: An introduction for developers page. You may also find the Telegram Bot API documentation helpful in this regard.

Once your bot has been created, you only need to add the channel ID and your bots' token to the IRIS Notification Group configuration.  An easy way to find your Channel ID is to send a message to @getidsbot