Question : How to popup a waraning dialog box in asp.net?

In my gridview_RowCommand event, after I query my sql database, if certain condition exist then I would like to popup a dialog box with some text message for the user.  Can some one show or point me to a url that how the code will be done?  Thanks.
I'm using VS2008, .net 3.5, asp.net and vb.
Thanks.

Answer : How to popup a waraning dialog box in asp.net?

use this

if some_condutions then
  dim msg="bla bla bla..."
  response.write("")
end if