How do I center align form

How do I center align form

How can I center align this form? I've tried, margin-left:auto;,
margin:50px;, margin: 0 auto 0 auto; and several other codes but nothing
seems to work. I want it so that everything is center aligned and if I
want to add additional items they will also be centered.
Here's the jsfiddle: http://jsfiddle.net/HrVaV/
Here's the css:
.radio div[type='radio'] {
background: transparent;
border:0px solid #dcdcdc;
border-radius:10px;
padding:0px;
float:left;
margin-left: 10px;
cursor:pointer;
}
.radio div.active {
box-shadow:0 0 2px 0px transparent inset;
}
.tablebuttons img {
width: 60px;
height: 55px;
border: 0px solid #666;
background: #fff;
display:block;
border-radius: 10px;
-moz-border-radius: 10px;
-webkit-border-radius: 10px;
}
.question {
margin-left: auto;
display: none;
clear: both;
}
.question:nth-child(1) {
display:block;
}
#linkDiv {
margin: 0;
}
.clear {
clear: both;
}