vb.net - recursive search for a file in all dir

Hi,

May I get some help on this topic?
How to recursive search in dir (sub-dir) under a root directory (C:\)
For example
Search file pattern is *.txt
Root  dir is C:\
This program will search all sub dir in root and
If found add file name to the array list
In vb.net code
Thanks..

Tomcy