Transparent Back Grounds

Hi Kathy,
I'm going to post to get the hang of this.  There are two things in PScs (I have 3) that I don't know how to do - or not well.  One is making a transparent background.  Let's say I have a photo of a machine from my vendor and they don't have it transparent.  I need to get ride of the white background and make the image a nice clean transparent.  I'm struggling with this.

Also, when I am editing photos (not so much my day job) I want to be able to airbrush.  I can do this on line in fun programs like Picnik.com, but I would really like to understand this in ps-cs3.  SO if you are teaching and want ideas...this is what I'm stumbling over.