here may be a good starting point.
http://www.guitartricks.com/trick.php?trick_id=8078

to play a chromatic scale:

Pick a string, any string.

Play the open note then play the note of the first fret, and then the second and the then the third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh and twelfth fret. There you have just played a chromatic scale over an octave.