How I can change the wireless channel on NETGEAR router?

https://kb.netgear.com/23783/How-do-I-change-the-wireless-channel-on-my-NETGEAR-router

 

There's a support site with access to manuals, firmware, install guides, etc.
Go to https://www.netgear.com/support/
Type in your model number and from there it'll take you to the above.
Its a great resource to start with.

Manuals are always a good place to start.

Visit the support pages:

Support | NETGEAR

Feed in your model number and check the documentation for your hardware.

Check the section in the manual Specify Basic WiFi Settings.

 

You don't say which device you own, but that is the default for most devices.