How can I close web when I want to upgrade it on wordpress.

I'm a newbie in wordpress. I used Joomla, it could close the page when i want to upgrade web. now i use wordpress so how can I close the page(I don't want anybody see it when i upgrade) how can i do?

So sorry, if my English writing is not good.

Thank you
Jack

Hello,

You have to use some maintenance plugins, please check these links:
https://wordpress.org/plugins/wp-maintenance-mode/
https://wordpress.org/plugins/search.php?q=maintenance

Install the plugin, go to plugin settings, write some text visible for guests, add you logo etc. activate the plugin and that's all. When your website will be ready, disable the maintenance mode.