How to Test, Inbound idoc ,with out the Sender System, using a Text File

Hi Guru's .

we wanted to test BLAORD03 inbound idoc (Message Type BLAORD).with out the SENDER SYSTEM.

on the same client.

we wanted to test this idoc with text file from our local machine.

Can anyone give us detail steps.like how to create File layout

with Segment name,and values for the fields.how to pass this file to the system.

Thanks in advance.