Free Mouse Over plugin questions

I’m having problems getting the mouse over to correctly work and have some questions: 1) what are icon 1 and icon 2 settings referring to? I have set up a photo gallery and would like to use mouse over on several different pics on the same page. How do I do that, assuming icon 1 is for one pic and icon 2 is for 2nd pic. Also, on the mouse over admin page it talks about plug in size, width and height. Does this have to be the same size for both the default image and the mouse over image? Don’t understand. Is there a tutorial somewhere that goes over the step by step workflow to get these installed and in working order. Thanks for looking, Gary