Below is a schematic of the first four frets on a guitar.  Picture the guitar positioned so you are facing the neck of the guitar  as you would if the guitar is in a guitar stand in front of you.  The low E string (thickest string) is on your left and the high E string (thinnest string) is on your right.

The thick horizontal line at the top of the neck (we'll call this schematic the "neck") is the nut, which is where all the strings pivot before finally making their way to the tuning heads.

The letters across the top of the neck are the notes of the "open" string.  In other words, if you pluck the string without pressing on any fret.

The numbers on the left side represent the fret number starting from the nut (string pivot point, or open position) ascending up toward the body of the guitar.

Now, the schematic of a chord will use this same neck schematic above but we'll add symbols to it which will signify which frets to press, and with which fingers to press them to form a chord.  For example, the cord below is a D major chord (later we'll learn why it is a D major).  Notice that when we say "pressing on a fret" it means that we're pressing on the string in the space between 2 fret bars as shown in the photo.

The red circles are the notes we want to play.  The 'X' means do not play that string, and the 1, 2, and 3 tells us to use those fingers to play the notes on each string (1=index finger, 2=middle finger, 3=ring finger, 4=pinky).  So, in the above chord, we play the open D string (4th string from the bottom of your guitar as viewed looking down at your guitar while you're playing it), along with the 2nd fret of the G string (3rd string), 3rd fret of the B string (2nd string), and 2nd fret of the high E string (1st string).  Play all 4 notes in one downward strum.

OK....that's the concept of the chord schematic and symbols.  Let's get in tune with each other!