how to setup a greeting message when start conversation.

[FehrHassan]

Please help me more
because the tutorial uses commands and i didn't get the actual effect of the command.
For example when i run this command
curl -X POST -H "Content-Type: application/json" -d '{
"account_linking_url": "ACCOUN_LINKING_URL",
"persistent_menu": {
PERSISTENT_MENU_SETTINGS
},
"target_audience": {
TARGET_AUDIENCE_SETTINGS
}
}' "https://graph.facebook.com/v2.6/me/messenger_profile?access_token=PAGE_ACCESS_TOKEN"

i got this message
{"result":"success"}
but i didn't get the actual effect in my bot.
So please help me, I am a beginner at building bots :D