Answer 1

You need to declare all your headers just like a normal mail but now as variable names eg

$to = '[e-mail]
$subject = 'Your Subject'
$message = 'Hello World!'
$headers = 'From: [e-mail]' \r\n

Then take your variables and put them in the mail() function

Not everything required in my answer may have been included because I haven't tried it yet but I'm sure it'll be of some help.