Remastersys is a curious application that allows you to create an image disk of any distribution featuring some extra data like software, screensavers or backgrounds.
That means you can personalize your own Ubuntu and create the installation disk to share it.
It isn't difficult to use if you use the Graphic User Interface. There, you should choose the distribution and what you want to add.
Choose whether to create a backup or to create a redistributable version without personal data.