This question already has an answer here:
I have 2 HDD in my computer at the moment... One 2TB HDD that is running Windows 8 and one 1TB HDD that I would like to install Ubuntu on. I bought the second HDD so that the two don't have to conflict with each other at all!
How do I install Ubuntu onto my second HDD, without affecting my first, and then when I boot up my computer, how can I choose between which OS to use? I have seen it at a friends house: they have a black screen on startup which they can then choose whether they want Windows or Linux.