do you mean width (rather than with) ?
Code:
Sub Column_Adjust()
Columns(2).AutoFit
End
the above would adjust column B to fit the text within.
Always worth remembering that for tasks like this the macro recorder will normally show you how to achieve your goal -> ie press record, do what you want to do manually, stop recording -- review the resulting code. This will often give you what you need for a trivial task and if not it will most likely point you in the right direction.