Web zones are receptacles for parts of a web page. You can use the following steps to change the width of a web part or zone if it is too large or too small.
To change the zone width with SharePoint Designer:
Select the checkbox for the web zone that you want to change.
Under Web Part Tools, click Options.
Select Web Part Properties.
Scroll down to the Appearance pane.
Under Width, click Yes to create a fixed width.
Type the new value and select Pixels or one of the other measurements. Note: You can also change the Height in the Appearance pane. by clicking Yes, entering a value, and selecting a measurement.
Click OK to save your changes.