Sub Submit_OnClick(sender as Object, e as EventArgs)
  If MyCustomMethod (txtUserName.Text, txtPassword.Text) Then    
      FormsAuthentication.RedirectFromLoginPage (txtUserName.Text, False)
  Else
      ' Invalid credentials supplied, display message
      lblMessage.Text = "Invalid login credentials"
  End If
End Sub

<configuration>
	<system.web>
		<authentication mode="Forms" >
			<forms loginUrl="login.aspx" name=".ASPNETAUTH" protection="None" path="/" timeout="20" >
			</forms>
		</authentication>
<!-- This section denies access to all files in this application except for those that you have not explicitly specified by using another setting. -->
		<authorization>
			<deny users="?" /> 
		</authorization>
	</system.web>
<!-- This section gives the unauthenticated user access to the Default1.aspx page only. It is located in the same folder as this configuration file. -->
		<location path="default1.aspx">
		<system.web>
		<authorization>
			<allow users ="*" />
		</authorization>
		</system.web>
		</location>
<!-- This section gives the unauthenticated user access to all of the files that are stored in the Subdir1 folder.  -->
		<location path="subdir1">
		<system.web>
		<authorization>
			<allow users ="*" />
		</authorization>
		</system.web>
		</location>
</configuration>

<input id="GetLocation" type="button" onclick="getLocation(<%=tbStreet.clientID %>.value + ' ' + <%=tbCity.clientID %>.value + ' ' + <%=tbState.clientID %>.value + ' ' + <%=tbZip.clientID %>.value,'<%=lblLocation.clientID %>');" value="Get Location" />