Select a mouse type which is nearest to yours. Most PCs nowadays come with 2-button PS/2 mouse. In Unix, 3-button mouse is better. In case yours is a 2-button mouse, select "Emulate 3 Buttons" checkbox. Besides generic mouse, there are newer and sophisticated mouses such as Logitech MouseMan, First Mouse, Microsoft IntelliMouse, and so on.
. . . press the "Next" button at the bottom to proceed.