I want to change the 404 page

I want to change the 404 Page but i get: This file could not be saved

create a file in your /htdocs folder called .htaccess then type
ErrorDocument 404 <URL HERE>
Please do not try to edit the main .htaccess in the folder /

> @TheCrafters said:

create a file in your /htdocs folder called .htaccess then type
ErrorDocument 404 <URL HERE>
Please do not try to edit the main .htaccess in the folder /

Thanks.