two authentication in a single application

 I have requirement to  maintain  windows as well as forms authentication  how can  i achieve this ? i changed my web.config file as below.

<location path="ScrollingText">
    <system.web>
      <authentication mode="Windows"></authentication>
      <authorization>
        <allow users="*"/>
      </authorization>
    </system.web>
  </location>
but i am getting an below error
ine 82: <location path="ScrollingText">

Line 83: <system.web>

Line 84: <authentication mode="Windows"></authentication>

Line 85: <author ...