What exactly do you mean? I suppose you have a form that the user fills out and then have it sent to an e-mail address?
Ok, you make your webform using HTML, then you'll best create another .php file that is going to handle the form.
In the FORM tag do something like this <form name='blahblah' action='php_file_to_handle_script' method='POST'>
Give all your formfields a name, you're going to use this name in the .php file that is going to send out your mail.
Then in your .php file you do something like this
$subject = "Subject_here";
$to = "recipient_address_here";
$body = "
Here_you_enter_whatever_text_is_going_to_be_in_the_email_body.
$_POST["formfield_name_here"]; // this is where you put the values that were submitted by the form.
";
mail ($to, $subject, $body, "From: your_email_addy" ); // mail() function sends the mail.
$POST["..."]; retrieves the formvalues that were entered by the user. Use $POST if your method was post. If it was GET, just use $_GET[...]; (mind the caps). Repeat this for every formvalue you want to display in your mail.
hope this helps! 🙂