How do I make my guild homepage/layout have that white blurry/cloudy effect?

What you do is put the following code in the box where you'd put news & etc:
<style>img {filter: Chroma(Color=#C1DEFF) Alpha(Opacity=200, FinishOpacity=0, Style=2, StartX=gradient start X , StartY=gradient starting Y , FinishX=gradient finishing X , FinishY=gradient finishing Y </style>

Black Jack at your service.