Edit Email Notification - Fields and Formatting

Hi, I tried to change the email notification that the system sends to users.
To do this I copied the file “it_IT.notify_template.html” from the /include/language folder to /custom /include/language folder.
I changed the lyrics and it worked well.
I would like to add other fields in the email notification from module, how to proceed?
Then let me know if you can customize the text formatting using HTML tags like </ b>.
Thanks for the support