A quick Google search pulls up the setTimeOut function:
<script>
$(document).ready(function() {
$("#DivStage2").delay(1000).fadeIn(1000);
setTimeout(function () {
$("#two").css("color" , "#fff");
}, 20000);
$("#DivStage2").delay(56000).fadeOut(1000);
});
</script>
I'd change the name of you h2 to 'one' and 'two' to avoid using numbers:
<div id="DivStage2" >
<h2 id="one">Topic1</h2>
<h2 id="two">Topic2</h2>
</div>