determining if the user is logged in

I am new to wordpress, and trying to get my head around the idea of sessions and all. I read in a lot of places that session concept is not used in wordpress. Anyway, I downloaded the my-login-theme plugin. My question is, when a user navigates to some secured area, I want to check if that user is logged in or not. Once I check that, I want to get user details like email, and full name. Is this possible in wordpress?

Thanks

Use the is_user_logged_in() conditional tag (Codex ref) to determine if the current user is logged in.

Use the get_userdata() function (Codex ref) to return user data.