How to clear fields of Dialog Box

Hi

I have used dialog box containing some fields to insert Guest Values to table. I have  added guest using Dialog_Box and inserted those values into to a table.When try for second time to add another guest. The Dialog_Box fields contains previous values. How to clear those fields .

Ex:-

When I clicked on Guest,  i checked for object for dialog Guest is there or not, if its already there, just i cald open() method if not i am creating it, then i ll call open method.

But when i try to create second guest , Dialog_box fields contains previous values

How to clear those fields ..?

Thanks