How to Increase Width of Sidebar?

Hi Jomala,
you can do that with Find&Replace plugin. After install you can find it in the WP-admin/Tools tab. Just replace
<div class="span3 left tc-sidebar"> with
<div class="span4 left tc-sidebar"> and
<div class="span3 right tc-sidebar"> with
<div class="span2 right tc-sidebar"> if you want to expand left sidebar with reducing right sidebar.
If you want to shrink content area instead right bar that replace
<div id="content" class="span6 article-container"> with
<div id="content" class="span5 article-container">

Thank you, Tomaja. I need to be more specific. I’m looking to increase the width of my left sidebar at a specific width that I choose.

In other words I do not want to put in pre-defined ratios. I need to widen the sidebar by about 20p.

I need to increase it because I’m trying to display an ad that is 300p wide. It seems that the left sidebar’s current width is a bit less than 300p, because the ad is getting cut off.

You must understand that this theme has responsive design, so its all about width in % with fixed ratios between elements. If you make left sidebar fixed your right sidebar will go under main content. So you can add e.g.

.left.tc-sidebar {
width:25%;
}

but that would be good just for high screen resolutions. So to keep it responsive, you will have to choose right span that fit your needs, maybe to exclude right sidebar (and then you can expand left sidebar even more) from showing or to wrap above code to @media queries, something like this

@media screen and (min-width: 1080px){
/* your code here */
}