Don't understand how to back stock rom tp-link C6 v3

Installing and Using OpenWrt
1

I want to back stock ROM but I can't understand how. Can anyone help me, please?

here is the link for information : https://openwrt.org/toh/tp-link/archer_c6_v3

2

Try using the TFTP method.

3

can you give me a video link

4

Do a search for "unbrick C6 v3"...