"The manual will help you become familiar with everyday tasks such as surfing the web, listening to music and scanning documents. With an emphasis on easy to follow instructions, it is suitable for all levels of experience."Their latest manual, Getting Started with Ubuntu 12.04, gives you a comprehensive walkthough of Ubuntu. It shows you how to install, get online, connect your email/social networks, etc. More importantly, It shows how to navigate Unity, because it can be hard for new users to learn the interface.
The Ubuntu manual is available to download for free, or you can order a printed copy for a small fee. The manual is open sourced licensed, so this means that it is free to download, read, modify and share. Essentially, do what you wish with it.
You can go here to get the manual. I'm going to try to embed the PDF below.