How do we log in iMessage

Turn on iMessage

1. Go to Settings  > Messages, then turn on iMessage.
2. To select which of your phone numbers and email addresses you want to use with iMessage, go to Settings > Messages > Send & Receive, then choose from the available options below “You can receive iMessages to and reply from.”
3. Set up Messages on iPhone – Apple Support

I can’t login into it. I keep putting my pass code, but didn’t work. I keep having Siri.