if windows was installed correctly, then it should have automatically have installed the mouse - one od the least troublesome pieces of hardware.
But your post is a little scant. What have you tried, in order to enable it?
1. Look in the device manger and right click the arrow by the "Mice and other pointing devices"
2. Right click whatever hardware item you see there (HID compliant mouse?)
3. Right click the properties of the device you see there, and click "Update driver software"
This may be enough.
Alternatively, in the Control panel, click "Mouse"
Work through the options in that panel. Post back anything you find, in any tabs, which are empty, particularly "Pointers"