Under Construction Page

I can see that u have this option in QUARK theme, but how to use it? is any plugin that u offer?? how I can work with wordpress and keep showing that page. Usually I use a plugin for wordpress, but in this case, what do I do?

It's static page, so you can redirect users to this page using i.e. this solution:
http://www.wpbeginner.com/wp-tutorials/ ... -a-plugin/

Thanks