How do I install Ubuntu inside VirtualBox? [duplicate]

Open VirtualBox and select New . A new window will come out.
Choose your guest OS and architecture (32 vs. 64 bit, e.g select Ubuntu)
Set your Base Memory (RAM)
Click next until it show the vm storage size. Put how much space you need depending on your hardisk and finish the wizard by clicking the create button.
On VirtualBox main window, select START and pick your MEDIA SOURCE. In your case, select the .iso on your desktop.
Finish the installation as normal install.
Remove your installation .iso from the virtual optical disk drive before restarting the VM.
Install Guest Additions.

Follow this guide:

Open Virtualbox and click at New button.

enter image description here

Setup Wizard will appear and click at Next button.

enter image description here

Enter your Virtual Machine name, and choose your guest OS and architecture (32- vs. 64-bit) from the dropdown menu and click Next button.

A 64-bit guest needs the CPU virtualization technology (VT-x AMD/V) to be enabled in BIOS.

enter image description here

Enter memory (RAM) to reserve for your virtual machine and click Next button.

Leave enough memory to the host OS.

enter image description here

Tick at Startup Disk and Create New Hard disk and click at Next button.

enter image description here

Choose the type of file that you want to use for virtual disk and click Next button.

enter image description here

Choose your storage detail and click Next button.

enter image description here

Enter the size of your virtual disk (in MB) and click Next button.

A dynamically growing virtual disk will only use the amount of physical hard drive space it needs. It is better to be rather generous to avoid running out of guest hard drive space.

enter image description here

You will see the detail of your input here. Click Create button to continue.

enter image description here

The "New Virtual Machine Wizard" will close and back to VirtualBox Manager. Select your Virtual Machine and click Start button.

enter image description here

"First Run Wizard" will appear and click Next button.

enter image description here

Click at 'folder' icon and choose your Ubuntu iso directory.

enter image description here

Select your Ubuntu iso file and click Next button.

enter image description here

In 'Summary' box, click Start button.

enter image description here

This screen will appear when it start boot.

enter image description here

After a successful installation we have to remove our installation .iso image from the virtual optical drive before we reboot. This can be done from the "Devices" menu or by removing the .iso from the VM settings:

enter image description here

For smooth graphics, and to be able to use shared folders it is recommended to install the guest additions.

Installing Ubuntu under virtual box

open virtualbox
than click New
then click Next
Set name something like Ubuntu 12.04 (it will automaticly set type to linux)
Set memory f.e. 1024 MB
Select Create new hard disk
Select VDI then Next
Select Dynamically allocated then Next
Set location(let it stay its default) and its size (f.e 20GB) then Next
Then Create
Then again Create
Here is two ways
- Install from .iso
- Install from DVD
Start VM
There select what kind of installation you want(from iso or from dvd)
then the installation will start