Setting custom error page for umbraco website

its very easy to set the custom error page for the website ....
1) first create the error page which you want to show...
2) Then go to umbracoSettings.config which is inside config folder .
3) You will find this tag in that file...

<errors>
      <!-- the id of the page that should be shown if the page is not found -->
      <!--        <errorPage culture="default">1</errorPage>-->
      <!--        <errorPage culture="en-US">200</errorPage>-->
      <error404></error404>
    </errors>

In this inside error404 write the ID of your created custome error page.

Its done ...now when error comes ..your page will be shown ....