You'll need to know how to turn it on and off to start with. That's often achieved via one of the 'Fn' buttons on your keyboard. (i.e. you need to look for a key that's got a camera icon on it and press that, together with the 'Fn' key, to toggle the webcam on and off).
Then you'll need to decide what you want to do with your webcam because you'll need suitable software for the specific task. So, for example, if you want to make video calls to friends across the world, you'll need Skype:
http://www.skype.com/en/
However if you only want to take pictures/videos of yourself you'll either need some suitable software (to do the job offline) or an online tool, such as Webcam Toy, which is explained here:
http://www.pcadvisor.co.uk/how-to/photo-video/how-take-picture-with-webcam-3473243/