Send XML order request to Kunaki.com

This should be a simple job for someone who understands PHP and how to send XML requests over the internet. I have a functioning order form that passes data to the attached PHP file. It emails a specified address with the order data. I want the attached PHP file edited to take the same data and instead send an XML request to Kunaki.com. Here's Kunaki's documentation: [login to view URL] - I'm interested in step 2: Request to manufacture and fulfill an order. - The product info will always be the same I do not prepay, but I will fully fund escrow.