WebWise
http://bbc.co.uk/webwise
BBC site that contains an "absolute beginners guide" to computing and a ten hour online course which teaches you the basics of using the Internet. You can even get a qualification at the end of it. Recommended!

Beginners.co.uk
www.beginners.co.uk
Lots of free online tutorials for many aspects of IT, including the Internet.

How to use the Internet
http://www.teachingideas.co.uk/welcome
Very easy to read step by step guides to using the Internet. Very basic and is designed for children but serves as a fun introduction for anyone new to the internet.

Learn the Net
http://www.learnthenet.com/english/index.html
Teaches you nearly all you need to know about the internet. Covers tutorials on email, web browsers, surfing the net and building a website and downloading files. There is an short online quiz to find out how much you know about the Net.

How to use the Internet and Email
http://www.wanadoo.co.uk/help/beginnerguides
Beginners Guide to the Internet and email. The Internet guide is fairly basic and does not cover things in much detail. The email guide is better and covers sending and receiving email and using email attachements. Plenty of screen shots to help you.