EDI inbound Idoc processing for testing purposes

Hi, I'm new to SAP and ABAP. I produced an ORDERS03 Idoc with my own app on a PC and I want to import and process it in SAP in order do test the contents of the Idoc.

I uploaded it with GUI_UPLOAD (in SE37), but I don't know how to process it from there. I did set up a customer in WE20 for msgtype ORDERS process code ORDE.

I was trying to invoke EDI_DATA_INCOMING, but it wants a filename on the server, and I don't have the means to put a file on the server, that's why I try to make GUI_UPLOAD work.

Can anyone point me in the right direction, or give me a URL with useful information. I read a lot on the forum but it did not help me further yet. Thanks.