this is how i did it:
1- go to
https://www.ubuntu.com/download/desktop and download the ISO from there
2-download Virtual Box. that i assume you already have it.
3-install Virtual Box.
4-then open Virtual Box and on the left top corner it should be a NEW bottom, so press it.
5-So when it opens you should type on the name i recommend on naming it "Linux - Ubuntu"(VB should recognize immediately that is Linux and is Ubuntu 64 bits version). and then you press next
6-then you can set the ram size so i recommend on putting it on 1024. press next
7-select the option that says "create a virtual hard drive now". press next
8-then select the first option VDI(Virtual Box Disk Image).Press next
9-select dynamically allocated. press next
10-the you select how much memory you want to use for your Virtual Machine. press next
note: be sure you download the ISO of Ubuntu 16.04 for 64 bits
11-after preparing for the installation, you can select the OS you want to run and press START on the top menu of Virtual Box.
12-it will ask you for the ISO you download so select it by pressing the folder image and showing where you ISO is. then press start
the it should start running the Virtual Machine with Ubuntu and you should be able to install Ubuntu just fine.
that is how i did it.
my recommendation is, i didn't liked the Virtual Machine with Ubuntu so i actually did a Dualboot and i totally loved it.
this is the video where i learn how to do it:
https://www.youtube.com/watch?v=4SbTXqPk_1Y
hope it works.
