Are you embarassed to admit you don't know any music theory? If so, stop it. There's nothing to be embarassed about. Lots of people pick up an instrument without ever learning the basics of music theory. You can learn a lot of stuff without ever knowing what you're doing. But if you're willing to learn the most basic elements of music theory, everything you do will make more sense.

Lesson 1: Sound Theory

This lesson introduces you to the physics behind music. It explains how vibration creates sound, and how certain types of vibration produce notes. In this lesson, you will learn:
Vibration
Frequency
Frequency Range
Pitch
Middle C / A440

Lesson 2: Music Theory

This lesson introduces you to the most basic concepts of music theory. Each topic is explained slowly and you are shown how they apply to the guitar. In this lesson you'll learn:
Octaves
Groups Of Octaves
Note Names
Sharps And Flats

Lesson 3: Scales

This lesson introduces you to the concept of scales, and explains the 2 most popular scales of western music. In this lesson, you will learn:
What Is A Scale?
Keys
The Chromatic Scale
The Major Scale
Note Numbers
The Minor Scale
Major -vs- Minor
How I Use Scales

Lesson 4: Music

This lesson introduces you to the basic structure of most blues and simple rock songs. The concepts in the previous lessons are brought into focus, as we look at how songs are built. In this lesson, you will learn:
Song Structure
Progressions
Simple Chords Structure
Chord Progressions

Lesson 5: The Blues

This lesson explains the basic structure of blues music, and how it relates to the larger world of music. Some common variations on the standard 12 bar structure are explained. In this lesson you will learn:
What Is I, IV, V?
12 Bar Major Blues
12 Bar Minor Blues
Turnarounds
Introductions
What Do You Play When?
The Pentatonic Scale