Arduino Due bootloader & ATMEGA16U2 FW

I have designed board same as Arduino Due on my project.

New board with blank ATSAM3X8EA-AU (New Chip) and ATMEGA16U2 (Usb serial converter same as Arduino due).

Can anyone guide me , how to burn Arduino Due boot loader (Arduini IDE) to access Arduino IDE?

Can you please explain in detail ,FROM TOOL MANU: which board should i select for ATMEGA16U2 ..etc?

p.s ICSP socket is on board and i have Arduino ISP as well.

Thank you.

I found that we cant burn bootloader on ATSAM3X8EA-AU as it burn in ROM by ATMEL.
We need to burn bootloader or load hex file for USB to serial converter.
I can see that PC doesn't find suitable driver for Atmeg16u2 DFU so we cant upgrade FW as suggested in link:

avrdude.exe ask for port number : -P /dev/ttyACM0 . black chip doesn't have boot loader so PC wont find port number.
Can anyone guide me what to do now?

I tried with Atmel Flip software to program ATMEGA16U2:

After programming hex file still Arduino IDE doesn't talk with it as missing driver or not Arduino IDE bootloader.

Any suggestion?????