Your webcam needs to be called upon by a program. (i.e. you actually need to be doing something with it!). That could be something like Skype (for making video calls) or it could be something as simple as using your webcam to take a photo of yourself. So we need to know exactly what it is that you want to do with your camera.
Once you're using some sort of software, that software might automatically turn the webcam on. However, if it doesn't, you'll need to do it manually. On most laptops that's achieved by looking for a key with a camera symbol on it and then pressing it at the same time as the 'Fn' key. (A light usually comes on somewhere, often next to the webcam itself, to tell you that the camera is turned on).