how to show message box with yes no button in asp.net

<script type="text/javascript" language="javascript">

function confirmmsg()
{
    if(confirm('message to display')){return true;}else{return false;}

}
</script>

Refer this
Conform using Javascript[^]

Hi Friend,

In Asp.Net the code is executed on machine of client.
So we have only one messagebox with "Alert". but you can create customized messagebox using Model Popup.

Or you can create a "Div" with position:absolute and keep its display property "none" when you need to show it out then change it to "block"

If you are using AJAX then model popup is the best option.

Thanks,
Chetan