1. Download and install the latest version of VirtualBox. (4.2.6 at the time of this article)
2. Download an ISO of the latest version of Ubuntu. (12.10 at the time of this article)
Note: If your current operating system is 32bit you must select the 32bit ISO. If your OS is 64bit, you can choose either the 32bit or 64bit ISO. If you are not sure, choose the 32bit.
Set up the Virtual Machine
3. Start VirtualBox and click New to create a new Virtual Machine.