Hi chan08 !
You do it following steps below :
1. You open index.php file in templates/ja_genista folder , find following code section at at about line 176 :
<?php if ($ja_right) { ?>
<div id="ja-col2">
<jdoc:include type="modules" name="right" style="xhtml" />
</div>
<?php } ?>
remove it .
2. Open template.css file in templates/ja_genista/css folder , find following code section at about line 856 :
#ja-colwrap div.innerpad {
background:transparent url(../images/vdot.gif) repeat-y scroll center top;
}
remove red text.
continue , find following code section at about line 860 :
#ja-col1 {
float:left;
overflow:hidden;
width:50%;
}
change to :
#ja-col1 {
float:left;
overflow:hidden;
width:100%;
}