I want to use Windows 7 or 8 but I don't know to install a software like VirtualBox which we have to do with the use of terminal. I don't want to use Windows as a main OS so I want to use it in VirtualBox. Can you tell me how to install downloaded files in Ubuntu. I once installed java runtime but don't know the meaning of the lines which I have written in terminal, I just did as the blog posted by a man says.