Here are the mandatory parameters needed for this call:

    "Source": "sample string 7",
    "SubSource": "sample string 8",
    "ReferenceNumber": "sample string 11109590",
    "ReceivedDate": "2017-04-19T14:18:36",
     "DispatchBy": "2017-04-19T09:18"

Please keep in mind that passing same source, subsource and reference number to an unpaid order will update it rather then create a new order.

For further information on datatypes please see the following documentation: