Click on the New button to start the Wizard.
Click Next and then enter the name of the Virtual Machine and select the operating system from the pull down list, then select which version of the operating system you wish to install.
Click Next, then select how much memory to allocate to your virtual machine. Some suggestions: Windows 3 to 98 = Anything less than 128 MB, Windows 2000 = 256 MB or more, Windows XP = 512 MB or more, Windows 2003 =800 MB or more.
Click Next and create either a new hard disk or select an existing hard disk from the list below. . You can use VHD, VMDX and VDI hard disk file types.
If using an existing disk, you can select it from the pull down menu, or click on the Folder icon and add the hard disk file to the library using the Virtual Media Manager.
Virtual Media Manager
Here is a sample of hard disk files in my media library.
If you want to create a new hard disk, click Next and the New Virtual Disk Wizard will start. Click Next.
Select the Hard disk type, either Dynamically expanding or Fixed sized storage. I recommend the dynamically expanding type and you will not run out of disk space later.
Now click on the Folder path and select the path and name of the hard disk file. By default, it will place them in the .VirtualBox folder in your user profile (E.g. C:\Users\username\.VirtualBox ), you can select another location if you need to.
Browse to the new location and enter the name of the hard disk file.
Click Next, on the Summary page click Finish.
Your new virtual disk now created. Click on the Finish button to complete the Wizard.
Your new virtual machine is now completed. Click Finish to complete the VM Wizard.
You can change any attributes of your new VM by clicking on the Settings button.
Click Start to load your new VM machine. For the first time it will start a First Run Wizard.
Click Next, select the installation media you need to install the OS. This can be a CD, DVD, Floppy or an ISO image.
Insert the media in to the host drive and click Next.
Click Finish and it will mount the new media and begin the setup process of your operating system on to the new VM.