How to display watermark or default text or PlaceHolder in Windows Mobile Application

Hey this is simple one,

but I dont know about design interface in windows phone, so help me!!

I have two textboxes

1 - email

2 - password

now how to show text written with "email" and when I run application

and take cursor in textbox then by default written text "email" should be disappear.

So how??

Thanks!!