STEP ONE: CREATE YOUR 404 ERROR PAGE

Create your error page which will be displayed when someone tries to access a file on your account that does not exist.

Now name this HTML document "404.html" and place it into your main directory (/home/yourusername/ftp/ ). Be sure this file has a .html extension rather than a .shtml extension.

STEP TWO: EDIT YOUR .HTACCESS FILE

Create with notepad a file named htaccess.txt,
Now copy and paste the following line into the top of your .htaccess file:

Upload it to the server, in the /home/yourusername/ftp directory, then using your FTP program's "rename" function, change it's name to .htaccess (a "." at the start, no ".txt" extension).

You are now finished and your error page should now work.