How to Login with the GWT Designer Widgets which connect to the server side Database

Hi,i have simple login application which is provided by the google, in that when we enter details it will display some message(the client side code).Now what i want is when i click on sign or login then it should go to server side and connect to the database and dispplay some message on browser.How can i do it..Can anybody give me some information about this issue please ....thank you..