This lesson from Expert Village is a very basic introduction to the notes on each string of the guitar, which will lead into the CAGED system.
Please have a look at my blog post on the CAGED shapes and make sure you understand the 5 shapes.
For further study on your own, check out Ernie Hawkins: C-A-G-E-D Guitar System Made Easy, Vol. 1 2 and 3
And/or if you’d like to study the CAGED system with me, check out Online Guitar Coaching