Hi Tapas,
To send and receive data within a BLE solution you must first understand the concept of Client and Server. A Server has data, a Client wants data. Since Client/Server is completely independent of the GAP role (Central/Peripheral etc.) you could have a server and client on both sides simultaneously.
Let's say you have implemented a server in your solution, by code you can use GAP_Notification or GATT_Indication to send data. (Example in SimpleBLEPeripheral)
Let's say you have implemented a client in your solution, by code you can use GATT_WriteCharValue to send data and GATT_ReadCharValue to read data. (Example in SimpleBLECentral)
Let's say you have implemented a client and server in your solution, you can use all above examples :)
Best Regards