Download an Ubuntu LiveCD image (.iso) from Ubuntu Downloads and burn it to a disc (see BurningIsoHowto). Insert the LiveCD into your CD-ROM drive and reboot your PC. If the computer does not boot from the CD (e.g. Windows starts again instead), reboot and check your BIOS settings by pressing F2, F12, Delete, or ESC. Select "boot from CD". Proceed with installation until you are asked this question: "How do you want to partition the disk?". Automatic partition resizing (recommended) Choose the first option, which should say "Install them side by side, choosing between them each startup". Specify the size of the new partition by dragging the slider at the bottom of the window. Click on "Forward". Continue on to Finishing Ubuntu Installation