Here's how to set a "fluid" width column in the TypePad blogging platform as mentioned here

Sign in to your TypePad Pro account.

Click the Weblogs tab.

From the list of your blogs (you can have multiple blogs with a TypePad Pro account), select the blog you want to work on, and click Design.

At the Design screen, click Change Layout.

For this example, I'm choosing 3 Columns Right, under the list of Classic layouts, click Save Changes.

Clicking Save Changes takes you back to the Design screen.  Now click Change Theme.

On the Theme screen, the radio buttom beside Pre-defined theme is checked by default.  Click the radio button beside Custom theme to change it.

This takes you to the Customize Your Theme screen.  This is an easy-to-use wizard that allows you to construct your own TypePad theme.  Click General Page Settings.

The Template Builder wizard will pop up.  At Main Content Column, Left column,  choose "Fluid" from the drop down list of column widths.  Note you can also change background colors, borders, border colors, and link colors with this wizard. 

When finished, scroll to the bottom of the wizard pop up window, and click Save Changes.

Clicking Save Changes in the pop-up wizard will return you to the Customize Your Theme screen.  Scroll to the bottom, click Save Changes. 

Click Save Changes in the Customize Your Theme screen will return you to the Design screen.  Scroll to the bottom, click Republish Weblog.

TIP:  Since TypePad Pro allows you to have multiple blogs, don't make design experiments on your live working business blog.  Create a new, different test blog.  Play with all the theme design features on the test blog. 

Once you're happy with the test blog's theme, you can just apply that finished theme to your original blog.  If you decide you don't like the new theme after all, you can switch back to your original theme.

Think of changing themes the same way you would like of changing a jacket.  It's not a big deal.  :-)