How to create a login form

Question

Hi,

I have created a window application. I have to provide security to it. I have to provide a login form with username and password. The username and password are present in the database. When i click the login button it should compare the username and password entered in the form with that in database and give access to the Window application that i first created. How to do it.
Please help

Nitin Raj Bidkikar