Virtual Machine
Firstly, you would have to download Virtual Box, the latest version from here:
https://download.virtualbox.org/virtualbox/5.2.8/VirtualBox-5.2.8-121009-Win.exe
Then install it, but you have to download the Linux Ubuntu .iso
file. This is the file you use to install ubuntu. After you have installed Virtual Box, you would have to create a new Virtual Machine. There is a video that shows you how to do create a new Virtual Machine and set it up.The link is at the end.
Basically, when you install the Ubuntu on the Virtual Machine, you are installing it in part of your memory. If you have 1 terabyte, you have enough to choose from, though you do not need tons. You decide that.
You can decide the RAM memory used by the Virtual Machine when it is on (all these settings can be edited later on) and the file.
I would download the latest version of Ubuntu (17.10), from the official website: https://www.ubuntu.com/download/desktop
Here is the link to the video:
https://www.youtube.com/watch?v=GGorVpzZQwA
Hope this helps.