Once the bootloader is burned on the 328p MCU, the board is ready to accept user sketches straight from the Arduino IDE or even through the command line via avrdudess/avrdude.
You may also add the W25X40CLSNIG 4MBIT FLASH-MEM chip (datasheet), this is useful if you plan to try wireless (OTA) programming, or want to use it as extra memory (like a small hard drive for your Moteino!).
To test the radio module, you will need another Moteino or a different board with an RFM69 radio – at least two are needed to make a communication link. Once ready, you can look at the many examples in the RFM69 library. For basic testing or a radio link you can use the Node and Gateway examples, or the TxRxBlinky example which can be used on both the sender and receiver units, along with a button for user interaction.