Can you please show how to do a close analysis of the themes, language, and theatrical techniques of Shakspeare's Macbeth?

Whenever doing a close analysis or "close reading," it's
good to choose a brief excerpt from the text rather than trying to range widely over
many words.  Here is a passage from Macbeth, chosen pretty much at
random, which we can look at closely. It comes from Act I, Scene 3. In this passage,
Macbeth is responding to the successful fulfillment of part of the witches’ prophecy
concerning him:

• Macbeth.
  [Aside]. Two truths are told, 240
  As happy
  prologues to the swelling act
  Of the imperial theme.—I thank you, gentlemen.
  
  [Aside] This supernatural soliciting]
  Cannot
  be ill, cannot be good: if ill,
  Why hath it given me earnest of success,
  245
  Commencing in a truth? I am thane of Cawdor:
  If good, why do I
  yield to that suggestion
  Whose horrid image doth unfix my hair
  And
  make my seated heart knock at my ribs,
  Against the use of nature? Present
  fears 250
  Are less than horrible imaginings:
  My thought, whose
  murder yet is but fantastical,
  Shakes so my single state of man that function
  
  Is smother'd in surmise, and nothing is
  But what is not.
  255

Note how in this passage, Macbeth is
already speaking in an aside, suggesting much about his character: that he has something
to hide, that he is privately ambitious, and that he is a man full of thoughts but is
not always willing to share his thoughts with others. Obviously, these asides already
foreshadow much of his later secretive, devious
behavior.

Meanwhile, his reference to the “imperial theme”
emphasizes a major motif of the play: his later desire to be king and to monopolize
power. The reference to “supernatural soliciting” also highlights a major theme of the
play, and it is interesting that Macbeth uses the noun “soliciting,” implying that he is
not yet won over to a full commitment to evil and implying, too, that he does not (and
will not) accept full personal responsibility for his own
ambitions.

The phrase “Cannot be ill, cannot be good”
typifies Macbeth’s tendency to vacillate, to see both sides to a degree that sometimes
paralyzes him. His is a deeply divided mind (at least at first), and Shakespeare implies
as much by using phrasing such as this.  The fact that Macbeth then develops the
implications of this phrase for the next several lines shows that he is capable of real
thought, and it also raises some of the major ethical issues of the
play.

When Macbeth refers to the unfixing of his hair and
to his

. . .
seated heart knock[ing] at [his] ribs,

Against the use of
nature . . .

Shakespeare
shows his gift for concocting vivid imagery while also anticipating, perhaps, the later
knocking at the gates of the castle.  Finally, this phrase also implies the theme of
unnatural behavior that is pervasive in the play. Characteristically, the passage ends
with more paradoxical language suggesting once more a divided
mind:

. . .
nothing is
But what is not. . .
.