How to flash apm for px4 to a development board?

Hi everyone,
I have a STM32F429 development board and a Segger J-Link, i want to flash apm for px4 to a development board, but i don’t know how to do these, my apm for px4 version is 3.2.1. Some people tell me the first step is to flash bootloader, and then nuttx. But i needed a more detail steps.
Can someone please help me?
My development board url is “http://item.taobao.com/item.htm?spm=a230r.1.14.130.7j9dk6&id=40779989300&ns=1&_u=71gjp4162c07&abbucket=13#detail”.

Thanks,
Junzai Han