In this case, you can do many ways:
A> First way:
1> Add node as the input of the service and select the service that you want to test.
2> From the Test menu, select Send XML File.
3> In the Select Test Mode dialog box, specify whether you want the service to run in Trace mode or Step mode and click OK.
4> In the Select File dialog box, select the local XML file that you want to submit to this service and click OK. Developer submits the file to the server, which parses it into a node object and passes it to selected service.
B> Second way:
Add a string named say inXML in the input of your service. Open the local XML file and copy the content and run the service and paste the content to the variable inXML. In this case disable the getFile step.
C> Third way:
Use the Load from file option while running your service but in this case you have to have your local XML in slightly format.