Does your installation contain the demo data provided by Oracle? If not, I would highly recommend getting it as it will give you some good examples of how the product can be used.
On the XAI Inbound Service configuration screen you will see a WSDL URL. Import the URL in SoapUI and you are ready to invoke the MDM web service exposed by the XAI Inbound Service. If your data cannot be added using the default BO's, you might consider creating a Service Script to combine some BO's. Again, expose the Service Script using an XAI Inbound Service and import the WSDL in SoapUI. Use SoapUI to map your input file against the elements in the web service call and this should work out just fine.