How to secure certain file types using Forms Auth?

right i am trying to prevent direct access to files in a certain folder without being authorised. e.g.

www.domain.com/secure/blah.csv

I have a root web config which:

 <location path="secure" inheritInChildApplications="false">
    <system.web>
   <authorization>
       <deny users="?" /> 
   </authorization>
  </system.web>
  </location>

<authentication mode="Forms">
   <forms name="login" loginUrl="default11.aspx" protection="All" path="/" />
  </authentication>

then one web config in the secure folder

<configuration>
    <appSettings/>
&nbs ...