submit button/post back

I  use submit button to post to database which successfully show in gridview but i also want to use thesame button to show a  post back as confirmatory page that you have successfully submited a post please, how can i go about the code to perform these function, i use property section of the submit button to do a post back to confirmatory page , the page show but message fail to show in grid view.
 a simple example of what i was trying to do is this, when u write a post in this forum now , u press a button to submit a post and a confrirmatory message is send to u. what is actually performing the two functions.

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