Here is a short tutorial on how to create a .htaccess page.
************************************************
Create Custom Error Pages
We'll start with the most common use for this file. This is
relatively simple in comparison to our next steps. Your
first step is to design your custom web pages for the
errors. They should keep the same template as your site,
but should inform the visitor that they experienced an
error.
The most common error pages are 404, 401 and 500. You
aren't limited to these errors as you could create an
error page for each and every error.
So now you have it complete. Great, next thing you need to
do is open up an ASCII text editor such as windows notepad.
Starting from the top of your page, write this:
ErrorDocument 404 <
http://www.domain.com/404.html>
ErrorDocument 401 <
http://www.domain.com/401.html>
ErrorDocument 500 <
http://www.domain.com/500.html>
Keep in mind to replace the URL's with the pages you have
just uploaded. Now you can try to save it as .htaccess,
but in my experience, windows does not allow it. Why?
Because there is nothing before the first period and only
an extension. Remember, this page is for an Apache server,
usually run on Linux or Unix. Windows does not understand
this at all.
Your solution is to save the file as htaccess.txt, then
upload it to your server. This file is uploaded into the
root of your public_html directory. Be sure it is uploaded
in ASCII form or it won't work. After doing that, you
should use your ftp client and rename the file to it's
proper name.
Now any errors that occur will be directed to the
appropriate pages.