3 monitor question

I have a client who needs to get a new computer which I am getting for her. She on the old computer that just died had 3 monitors connected. One with a double cable. One separate VGA connector. The new one will have the same. My question is when I connect the 3 monitors to it. How do you open a program and see it on another monitor and still see the desktop on the first monitor?
She will have Windows's 7 pro sp1
I never did a hookup with more than one monitor except on a laptop
And that went automatically
Thanks

Just so you know, I opened up a program on monitor 1, it showed it on monitor 1, so how do I open it to show on monitor 2 and 3. Do I just click it to open on 2, or 3.
How do you move the mouse over to each one? Does that also just go automatically?
And when I connect easy monitor will I automatically see each desktop on each monitor?

bassfisher6522 said:

You need to extend each display.

How do u do that?

Thank you