How do I bring the Ubuntu iso into virtualbox ?

[Alpine]

High this is my first time with virtualbox. I am assuming I have the right set up but am not 100% sure after reading various things including Virtualbox install guide. I am currently trying to get my downloaded Ubuntu 12.04 bittorrent iso file into virtualbox but cannot see how to do this through settings and storage. I assume I use IDE but get errors when I try from that point onwards. Can someone perhaps help direct me or at least tell me what extra information you need to help me to install Ubuntu into my virtualbox. Do I use the storage setting to do this I should add ? My primary host is Ubuntu 12.04 and my guest host is 12.04 also.

Many thanks for your help.

[BillG]

You simply attach the .iso file to the CD drive of the virtual machine.

[mpack]

In Storage settings, select CD drive in left panel, media for it in right panel.