Help on remote access of computers


I've been interested in trying to remotely access computers lately but I'm having a lot of trying finding out how to do it. At home we he have 3 computers, a Mac which I believe runs Tiger, a PC running Windows 7 and my Macbook Air running Snow Leopard. I understand the process of it and parts of it, like that I need a VNC application and I have Chicken of the VNC downloaded but I don't really know how to use it. Can anyone give me some info on how to do this? I have the IP addresses of the computers but I don't know exactly how I need to use them.