1. First Identify name of the transaction FOR DOING bdc 
session.
2.Write a program to built a bdctable,that will be used to 
submit the data into SAP.

3.Final Step is Submit the BDC TABLE INTO system using 
single transaction (CALL TRANSACTION) OR SESSION METHOD.

1.Flat file creation(ex. text file or excel file).
2.Declare internal table and bdc structure.
3.Upload the data to internal table(ws_upload or gui_upload)
4.Upload the data to the corresponding screen from internal 
table.
5.open bdc
6.insert bdc.
7.close bdc.