How to create a third column

There are many good tutorials for this. One example is the dummies guide to google blogger beta (see link list). Anyway, for the purpose of my record, I am just writing this post. I omit other details in the CSS code to avoid clutter:


#outer-wrapper {
width: 1000px;
}

#main-wrapper{
float: left;
width: 55%;
}

#sidebar-wrapperR{
float:right;
width: 20%;
}

#sidebar-wrapperL{
float: left;
width: 20%;
}

In the HTML code:
<div id='outer-wrapper'>
.
<div id='main-wrapper'>
<div id='sidebar-wrapperR'>
<div id='sidebar-wrapperL'>
.
.
</div></div></div></div>