Your mouse will usually have been auto-detected by the installer, and the settings will be displayed here (see Figure 1.3). If your mouse hasn't been detected (perhaps it wasn't connected to the computer at the time?) you can set it up manually. Select the correct settings from the TYPE and PROTOCOL lists (and in the case of a serial mouse, the COM PORT). Then activate the APPLY SETTINGS NOW button.
You can test your mouse is functioning correctly by moving the pointer into the mouse picture in the lower right of the screen. While your pointer is in this region, pressing the buttons on your mouse will cause the corresponding areas of the diagram to turn black.
Having three mouse buttons is very useful under GNU/Linux. If you have an ordinary 2-button mouse, the installer will help it impersonate the fancy 3-button kind. You get the effect of the "middle button" by pressing both the left and right mouse buttons simultaneously. Try it out in the test area!