Which upgrade version do i need for Archer C2600 router

I installed openwrt to test for fun.. it worked fine and since then, I have only been able to manage/change my ISP details and change wifi passwords.
Rest everything is bounced off my head.

However I wish to upgrade my router software.
This is my existing router details:

Hostname LEDE.2X.0.7
Model TP-Link Archer C2600
Architecture ARMv7 Processor rev 0 (v7l)
Firmware Version OpenWrt 18.06.1 r7258-5eb055306f / LuCI openwrt-18.06 branch (git-18.228.31946-f64b152)
Kernel Version 4.14.63
Local Time Mon Jan 20 23:49:34 2020
Uptime 6h 12m 30s
Load Average 0.34, 0.25, 0.18

Please guide me to write/correct software link and also guide on taking backup in case something fails.

Please check your router's device page in the wiki, it should have all the information necessary.