Thank you, can I ask you where did you get env['mail.channel'].browse(22)?

I'm still newbie and learning it, can you recommend any youtube/tutorial to watch? or docs?

Hello, I get this error

This is my url

https://motorcycle5.odoo.com/web#id=3&menu_id=77&cids=1&action=115&model=discuss.channel&view_type=form

'# Available variables:\n# - env: environment on which the action is triggered\n# - model: model of the record on which the action is triggered; is a void recordset\n# - record: record on which the action is triggered; may be void\n# - records: recordset of all records on which the action is triggered in multi-mode; may be void\n# - time, datetime, dateutil, timezone: useful Python libraries\n# - float_compare: utility function to compare floats based on specific precision\n# - log: log(message, level=\'info\'): logging function to record debug information in ir.logging table\n# - _logger: _logger.info(message): logger to emit messages in server logs\n# - UserError: exception class for raising user-facing warning messages\n# - Command: x2many commands namespace\n# To return an action, assign: action = {...}\n\nchannel_to_message = env["mail.channel"].browse(3)\n\nfor lead in records:\n message = "Lead %s is created" % lead.name\n channel_to_message.message_post(body= message, message_type="comment", subtype_xmlid="mail.mt_comment")'

Seems like model name is different in the odoo version you're using. So,

instead of using
channel_to_message = env["mail.channel"].browse(3)

replace that line with
channel_to_message = env["discuss.channel"].browse(3)

This change should work.

Thank you Karan, it works, can I ask final question? Where can I learn these kind of things where you can manipulate the data like the python code you put? Where does env came from?

You can search for online tutorials for particular topics. However there is not a single tutorial to follow. Also, you can learn things from Odoo's developer documentation itself.

https://www.odoo.com/documentation/16.0/developer.html