[Firefly-RK3288] How do I boot from sd card?

I want to boot with sd card

I want to know how to put u-boot, kernel, rootfs on sd card
Thank you

http://wiki.t-firefly.com/index.php/Firefly-RK3288/Boot_Ubuntu_from_sd/en

isle Posted at 3/6/2017 09:10
http://wiki.t-firefly.com/index.php/Firefly-RK3288/Boot_Ubuntu_from_sd/en

Thank you
But I want to put in a file I built