Hi Amal,
On high level, below is the mapping between objects in ECC and APO via CIF -
1. Plants/Cust/Vendor - Locations in APO
2. Capacity - Resource in APO
3. Routing and BOM - PPM/PDS in APO
4. Purchase Info record - Transportation Lane in APO
For detailed mapping and undearstanding, please refer the SAP Help - it gives good details.
Hope it helps.
Regards,
Alok