How to change the label's text's font size

["chao yeaj" <yeajchao gmail com>]

Hello everyone

   You Know,the label widget displays text
   I want to change the Font Size of the label's text,
   But i did not know how to do that.

   I found somebody change the font size using
   <...small ...>
   <...large ...>

   But i want the change the font size to a certain size ,not just
larger or smaller than the font size usually is.

   I need your help
Any comments would be much appreciated ,and thanks in advance!