How to set up any page as custom 404 page

For set up custom 404 page you have to follow the below instruction :

1.At first you hover Plugins and go to the Add New.

2.Then search 404 page and install "All the Pages Redirect to Homepage" plugin and Activate the plugin.

3.Then hover the Settings option and click the "All the Pages Redirect to Homepage" plugin.

4.And finally you have to Enable the status and set the 404 page URL which you want to set and then Update.