popup window for login

Question

I want to create a login page and this should be a modal dialog .

and when the login hyper link is clicked the popup window want to come.The hyper link  is in the master page.  

In the login page when the login button is clicked the values should be verified with the database.

And the value of the username want to be displayed in label in the master page.  

 

when the cancel button is clicked the dialog box should be closed.

pls help me with sample codes and examples.