Sample web.config for a basic forms based authentication web application that is using membership and role providers.

web.2.0.config

<?xml version="1.0"?>
<configuration>
  <appSettings />
  <connectionStrings>
    <!-- you'll need to change this to match your server - the one below is using the default local instance with Windows Auth. -->
    <add name="aspnetmembers" connectionString="server=.;initial catalog=AuthDemoApp;Integrated Security=SSPI"/>
  </connectionStrings>
  <system.web>
    <compilation debug="true"/>
    <authentication mode="Forms">
      <forms loginUrl="Login.aspx" defaultUrl="~/Secured/Default.aspx" requireSSL="true" />         
    </authentication>
    <membership defaultProvider="SqlProvider">
      <providers>
        <add name="SqlProvider" 
              type="System.Web.Security.SqlMembershipProvider" 
              connectionStringName="aspnetmembers" 
              applicationName="AuthDemoApp" 
              minRequiredPasswordLength="5"
              minRequiredNonalphanumericCharacters="0" />
      </providers>
    </membership>
    <roleManager defaultProvider="SqlProvider" 
                  enabled="true" 
                  cacheRolesInCookie="true" 
                  cookieName=".ASPROLES" 
                  cookieTimeout="30" 
                  cookiePath="/" 
                  cookieRequireSSL="true" 
                  cookieSlidingExpiration="true" 
                  cookieProtection="All">
      <providers>
        <add name="SqlProvider"
              type="System.Web.Security.SqlRoleProvider"
              connectionStringName="aspnetmembers"
              applicationName="AuthDemoApp" />
      </providers>
    </roleManager>
  </system.web>
</configuration>