edit style.css of the theme:
increase each of the big numbers in these lines in the following styles by the same absolute amount:
for instance change:
margin: 0 -240px 0 0;
to: margin: 0 -310px 0 0;
margin: 0 280px 0 20px;
to: margin: 0 350px 0 20px;
width: 210px;
to: width: 280px;
#container {
float: left;
margin: 0 -240px 0 0;
width: 100%;
}
#content {
margin: 0 280px 0 20px;
}
#primary,
#secondary {
float: right;
overflow: hidden;
width: 210px;
background:#eee;
padding:10px;
margin-right: 10px;
box-shadow: 0px 0px 2px rgba(0,0,0,0.5);
-moz-box-shadow: 0px 0px 5px rgba(0,0,0,0.5);
-webkit-box-shadow: 0px 0px 2px rgba(0,0,0,0.5);
-moz-border-radius: 4px;
-webkit-border-radius: 4px;
border-radius: 4px;
}
hope the explanation is followable ??