You got a driver CD that comes with the camera.
Install the drivers and the software that comes with the camera (I looked into the manual and it only has drivers for Windows 98SE/ME/2000/XP).
(If you don't have it: Download the drivers and so on: http://www.mustek.com.tw/html/prod_camra/5lf_st2.html)
Sometimes you also need to switch inside the cam's menu somewhere to "PC" (or whatever they named the mode)
In the end you need a webcam software to use a camera as a webcam, if there is nothing on the Mustek drivers/software CD/DVD then you need to download some freeware stuff.
Google is your friend. ;-)