A link is provided in the Files area of this page called Tuning 101. It is a slideshow that gives a general overview to the tuning process for absolute beginners.
Also in the Files area, is an online tuner. This page is available to identify pitches for you and help with the tuning process, no download is necessary. The website uses your computer's microphone and speakers.
There is a video in the Files area that demonstrates how to tune using a tuner.
Lastly, a link is provided for an tuning app that your can download to your device if you choose.