Go to the worksheet where you want to have this functionality, right click
the tab at the bottom of the worksheet and select View Code from the popup
menu that appears, then copy/paste the code Gary''s Student posted into the
code window that appears. If Column A is not the correct column (you didn't
tell us what column you were interested in, so Gary''s Student guessed at
Column A), then change the "A:A" argument in the Range("A:A") function call
to the column letters you actually want. That is it... when you type an
entry into Column A (or whatever column you change it to), the column will
automatically "AutoFit" when an entry is made into it. By the way, you can
use this simpler code I posted back to Gary''s Student in place of the code
he offered you.
Rick