If you want to learn to play the guitar, but can't afford lessons - or just want some additional help - visit this website for some great easy to understand beginner guitar lessons. 

It starts by teaching you how to hold a pick and how to hold the guitar and then moves on to playing.  There are also lots of pages on music theory where you can learn about chords, how the scale is set up, and lots more.  

I don't know a thing about music, but this site explains things to easily that even I can understand.  Each section also has recommended reading for people who want to learn more - with reviews of guitar lesson books, music theory books, etc.  

And, if you are interested in buying a guitar or need some advice on strings, capos, cases, etc. there are reviews on all that stuff as well.  

The beginner guitar lessons are my favorite though.  There are a few posted right now, but they seem to be adding more all the time.  I would say any child over the age of eight or nine could easily understand these if they have a desire to learn how to play the guitar.