1. Open your VirtualBox application. On starting screen, click on New icon.

2. Welcome screen will appear. Click Next button to create new virtual machine.

3. Fill up your virtual machine name. For example , in my case i want to create Windows 7. So, i naming it as a “Windows 7”. After that, select the Operating System Type and Version. Click Next button to proceed the next step.

4. On Memory screen, you can adjust your memory size or just leave it the default size. Then, click Next button.

5. On this screen, select “Create new hard disk”. If you already have the virtual machine, select “Use existing hard disk”.

Click Next button.

6. Click Next button

7. Select “Dynamically expanding storage” and click Next button.

8. Customize your hard disk size by drag the cursor to maximum number and click Next button.

9. Verify the setting and click Finish button.

10. Now, your virtual machine ready to use. This tutorial not covered  the OS installation. See the next topic to learn how to install the Operating System

Next topic :

a) How to boot installation CD

b) How to Install Windows