I would like to know how to transfer pictures?

I have done this years ago, but I cannot rememb er how to do it now. I would like to transfer pictures from my printer, no matter what size, to my computer, and the computer will resixe the pics to conform to the sixe needed. Then I would transfer the pics to a different web site as I want. One pi cture a head shot for example, and the other just fooling around in front of a sales booth.