Function Module

Hi Friends Please help me to resolve this, would really be very kind of all of you.

Requirement. I want to Enhance the field ZFACTREG from VIBDBE table in my datasource 0busentity_attr extract structure l_s_REIS_BUSENTITY_ATTR, I want to create the logic in CMOD exit_saplrsap_002 to call my function module for enhancement of master data. Please help me Step by Step

Please refer to my other post "Function Module Call Via CMOD Logic for Master Data Enhancement" for the code

Thanks

Poonam Roy