Newsletter subscription with ajax dialog box

Hi,

Just new to asp.net and ajax.  i have newsletter subscription textbox and submit button on default page.

i want it functionality with ajax. when user enter email address and click button it check email address from database if exits give msg already exits.

if not save in database and pop-up dialogue box just like on linkedin to say confirmation message and button to close popup dialog box.

all in ajax without refreshing main page.

so please help me......