I really like Zenphoto CMS, but when I try to make some pages on my website, I couldn't find the Zenpage plugin. as it shows 404 here https://www.zenphoto.org/documentation/plugins/_zp-extensions---zenpage.html
where can I find the plugin?

It is part of Zenphoto, you have to enable it. If you have that URL you are probably on an outdated Zenphoto version.

thanks, I have found it.