I have bought a Microsoft Lifecam VX6000 Web Cam with a built-in mic?

Please could someone tell me how to chat and be able to l ook at my friend or the screen and she be able to see me as well. My web cam has got a mic built-in to itand the Operating System is Windows XP. The programmes I would appreciate some help with are Yahoo Messenger and Windows Live Messenger. I am not really computer literate and would really love some help on this. Thanks for your help in advance.