This will be a tutorial on how to create a virtual machine in Virtualbox.
Step 1: Step One
Step 2: Name Your Virtual Machine and Choose the Type of OS You Will Be Using.
Virtualbox will automatically choose the best option for you based off of the name. If you are unsure, use the magic Google.
Step 3: Now Configure the Amount of RAM You Will Need.
For Ubuntu desktop, you will need about 1GB.
Step 4: Configure Hard Disk
You will need to choose to make a hard disk. Choose what I have selected.
Step 5: Choose the Type and Size.
What I have shown is the best option.
Step 6: Choose Your ISO to Boot From
You will need a .iso file to boot from to install an OS
Step 7: Now You Are Ready Start the VM
Once you have started your VM, you should be able to choose your options to install your OS with no issues at all.
Step 8: There You Go!
You have now created a VM in virtualbox.