onclick event of the Button, write a JavaScript which will get the div element by it's id and set it's display property to none.
<input type="button" id="submitButton" value="Submit" onclick="javascript:showDiv();" />
Here goes your javasciprt function:
function showDiv() {
document.getElementById("divID").style.display = "block";
}
I think there is more than that you want... possible you want to validate your controls before posting back. That is very simple too. Just check the values for required elements and return a false/true to the function based on that.