Attaching files to submitted forms

[Jamcan]

I have a form that my guest fills in with requested info. it involves php files and the actual form in Html. How do I allow the user or guest to attach a file from his hard drive for submission with the form when they hit submit.

Thanks
Timmytiger32@hotmail.com

PS. I want the file to be email to the address the form information collected is email to. this is define in the php as $mailto = 'timmytiger32@hotmail.com' ;

[Twey]

The form:

<form enctype="multipart/form-data" action="whatever.php" method="post">
  <input type="file" name="userfile">
</form>

The PHP code to use depends on what you want done with this file.