Installing ubuntu from the live-cd these days is too easy, really: insert usb stick, boot, install. Done.
The ability to try before installing is just the icing on the cake. You check if all your hardware is supported (especially network, display, mouse/keyboard) and go…
If you installed it next to the preinstalled Windows and the latest update destroyed your GRUB bootloader config (or any other), use the same live-cd/usb stick to recover.
just run these lines in a terminal and let the repairing begin:
sudo add-apt-repository ppa:yannubuntu/boot-repair sudo apt-get update sudo apt-get install -y boot-repair && boot-repair