What is an error page?
An error page appears when you have misspelled a page or the page you requested has been deleted. When the user is being referred from another site or by any other way, this could cause the user to just hit the “back” button and not go into your site. That, is not good.

Step #1: Create the error page however you’d like. An image or just a text, but make sure you have somewhere they can click to continue to navigate your site. After that save it as you save any other page.

Step #2 Locate your .htaccess file on your server. It should be in the main directory. Download it to your computer and open it in notepad. If it’s not there just open notepad.

Step #3: Type: ErrorDocument 404 http://www.domain.ext/yourerrorpage.ext . Substitute the url I put with the url for the page you created. After that, upload it. If you opened a blank notepad page, than click ’save as’ and in the filename type “.htaccess” with the quotation marks. Upload it, and you’re done!