Implementing BADI BBP_CTR_BE_CREATE in SAP SRM to transfer values to ECC system

Hi Experts,

I want your help in implementing the BADI BBP_CTR_BE_CREATE. This BADI will be called when we transfer contracts from SRM to ECC. I want to map the field SRC_OBJECT_ID into another field in ECC system. I'm a beginner and I find it a bit confusing.I'm using the method CONTRACT_INTERFACE_FILL. Can you please help me out with the steps?