There is a link to the official Ubuntu installation guide near the bottom of the download page at Ubuntu.com, as of 2015. This page gives a step-by-step overview of how to install Ubuntu from either a USB drive or a CD. The official installation guide ends once the basic installation is complete, and if you are new to Linux, you may want to find a customization guide as well.
The official guide covers the basics of installing Ubuntu and also allows you to set up an Internet connection and automatic updates. For a more in-depth guide, you can search Google for a community-created installation guide. The Linux community is very active, and you can find answers to most questions on the official forums or through Google.
The Ubuntu installation guide on MakeUseOf.com is another great resource when installing Ubuntu. It also covers the basic installation steps, but it additionally includes customization options. This guide also covers dual-boot, the software explorer, every aspect of the user interface, and how to perform basic tasks such as listening to music and editing images. In addition to instructions, this guide offers an in-depth look at several aspects of Ubuntu. It explains what Linux and Ubuntu are and how they are funded.