Dear Sweta,
It is recommended to share links or documents in SDN.
Still if you want kindly search with text ' Step by Step Guide to Enhance a Data Source'.
Data-source enhancement can do in 2 ways:
1. Thriugh CMOD exit at ECC side using FM -EXIT_SAPLRSAP_001
2. Through BADI - RSU5_SAPI_BADI.
Best wishes, Vijay