How to make my built-in webcam work?

Hi, my auntie recentcly purchase a compaq hp comeputer for me. I told my dad to tell her to buy 1 with a built in webcam or camera or whaterver you call that can take videos and pix. My cousin has a dell laptop and has a camera thats built in. All she needs to do is go on a bar on top of the home screen that has a pic of a camera and click it and she can start taking photos and/or videos. I wanted mine like that too. So my auntie buys me the laptop and I KNOW it has a webcam but I do not know how to use it. My laptop is a Compaq Presario Notebook thingy. Please tell me how to work the camera and everything. Thanks.