Dum Question

[Gerald]

Running Mac OS when I download a program from Version Tracker or Tucows it 
untuffs automatically with stuffit. I downloaded a program for YDL and now 
I don't really know what to do with it. It is a tar.gz file or something 
similar (I know, I know I'm on a different computer with a bad memory) How 
do I unzip or unstuff a file in Linux? Waiting for your reply and remember 
this is a newbie list.

TIA,

Gerald