Is your machine a 2005 iBook or a 2006 MacBook? VMWare will only work on Macs with an Intel CPU, which generally means ones made from 2006 on. If you click on the Apple at the far left of the menu bar and choose "About This Mac", be sure the Processor line includes the word Intel.
If your machine is supported, I agree that you will find it is very easy to get it installed. Creating a virtual machine (running Windows, for example) is more involved than installing Fusion itself, but there are tutorials on the Internet that should help get you going.