Restrict User to open other Webpages without Authentication using Forms Authentication in ASP.Net

I tried to follow the examples give in :

http://www.codeproject.com/Articles/98950/ASP-NET-authentication-and-authorization

So in my web.config i typed this :

<authentication mode="Forms">
<forms loginUrl="Login" defaultUrl="DailyLog" timeout="2880" cookieless="UseCookies" />
</authentication>

when i browse my application through local host , it shows Login screen , also validating the credentials , but without entering any credentials if i change my Url at login page from :

http://localhost:49702/Login 

to

http://localhost:49702/DailyLog

it goes to DailyLog without confirming the login ... 

in Login Screen on Submit button Click event i have done this :