Go into HTML mode in the WP editor and put something like this there
HTML Code:
<div class="post-left">
... Content ...
</div>
<div class="post-center">
... Content ...
</div>
<div class="post-right">
... Content ...
</div>
And at A. Theme Options -> HTML/CSS Inserts -> CSS Inserts add
HTML Code:
.post-left,
.post-center,
.post-right {
float: left;
width: 32%;
}
.post-left {
padding-right: 1%;
}
.post-center {
padding-left: 1%;
padding-right: 1%;
}
.post-right {
float: right;
padding-left: 1%;
}
You can then re-use part one (putting the div's into the WP editor) and do not need to add the CSS insert again