I have a form that needs to require the upload of a jpg file before moving on to step two. What is the value I need to require, currently it is set to

$form["labels"]["9"] = "picture";
$form["names"]["9"] = "picture";
$form["fields"]["9"] = "file";
$form["types"]["9"] = "file";

Also do I need to post the picture into an upload script?

Chris