What you have described here where you have a file field on the form to upload a file and send it as an attachment is not something that the contact form solution will do for you. The upload functionality would need to be manually applied using our Digital File Pro tool. You could then configure the email message to contain the newly uploaded file. We have a guide that covers this exact setup but the guide requires you to use the Digital File Pro and Universal Email tools to accomplish this.
If you would like to manually add in an attachment to the message you can do so in the WAUE_contact_1.php page, at the top of this page you will see the attachments variable, you can set this variable to be a path to a file to have that file attached to the message. The path must be to the file on the server though. Here is an example of what that might look like:
$MailAttachments = "/home/files/the_file.pdf";