Using cookie plugin to branch

Using cookie plugin to branch

The user first enters a user name and password via a PHP script where an expiring cookie is set (i.e. 30 minutes).  I want to prevent others from entering the pages unless they have properly logged in (this is not a high security site; just images that are preferably for the staff).

The syntax of reading the cookie is straight forward: $.cookie( "my_cookie" ).  I am not sure of the syntax so that the user would be taken to "index.html" if the cookie value is not present.

Many thanks...

Todd