After that, visit the download page and get the Virtual Box packages (below VirtualBox x.y.z platform packages) and the extension pack, too (below VirtualBox x.y.z Oracle VM VirtualBox Extension Pack).
Now install and start Virtual Box. You should see something like figure 2, but without those VM “Ubuntu 1810”, that I already set up.
Klick on Preferences>Extensions>adds new package to add the extension pack (see figure 3). It provides some additional features like the shared folder, which I mentioned above. The green tick below the active tab marks a succesfully installation.
In this post, I like to emulate Ubuntu by way of example, so go to the Ubuntu dowload page and get your ISO-file of Ubuntu (at the time of writing the latest version is 18.10 – Cosmic Cuttlefish )
You are now ready to set up our virtual machine. Go back to the front page of your Virtual Box Manager, click new (figure 4).
Give her a nice Name, adjust the Memory size over 2 GB, enable Create a virtual hard disk now and click Create (see figure 5).
The minimum File size should be over 25 GB, even if you don’t plan to store much data. As Hard disk file type you can choose the Virtual Box native file format VDI and you probably want a Fixed size for your Storage on physical hard disk, because dynamically allocated storage could slow our guest machine down (see figure 6). Dont panic, if you reach your disk size later on, there are ways to expand it. Click Create. Depending on your hard disk, this could take a few minutes.