Doubt rearding bdc

Hi,

I am trying out BDC using session method. I am trying t upload 4 field values from a txt file on desktop to sap.

when I process the session it still calls the screen and asks for the values for vendor creation...why does it not take values directly from the txt file? I tried running it in both foregrund and background In case of background it ends up with incorrect transaction.

I do not understand

1.what the parameteer transaction code in bdc insert means

2.when we say perform [subroutine] using [program name] [screen no]- which is this program and screen number?

The transaction code that I created uses the program SAPfm02k and screen 100.