In Julius Caesar, were there 3 shouts praising Caesar?Or were there 2 shouts praising him and the third was the crowd booing?

It is always a good idea, when asking about a specific
moment in a play to cite the Act and Scene to which you refer.  I will assume here that
you refer to Act I, scene ii when, as Brutus and Cassius talk, there are shouts heard
offstage from the direction in which Caesar has gone to observe the
games.

The number of shouts that are heard by Brutus and
Cassius is, dramatically, an interesting question.  It is most important to refer to the
text, the lines spoken by the characters, when determining action or sound effects. 
Shakespeare, if he intended that some necessary action or sound occur, always had
characters make reference to it.  We have no proof of any kind that stage directions you
might find written in your edition of each play were, in fact, the work of Shakespeare. 
So, it is always the safest course to rely on the words spoken by the
characters.

During his conversation with Cassius in Act I,
scene ii, Brutus mentions the cheering of the crowd twice.  The first mention is at line
78:

What means
this shouting?  I do fear that people

Choose Caesar for
their King.

And again at line
132:

Another
general shout!

I do believe that these applauses
are

For some new honours that are heap'd on
Caesar.

Shouting is not
mentioned in the scene again until Caesar has re-entered and exited, leaving Casca alone
onstage with Brutus and Cassius.  They talk about what Casca
witnessed.

readability="19">

Casca

Why
there was a crown offered him.  And being offered him, he put it by with the back of his
hand, thus.  And then the people fell
a-shouting.

Brutus

What
was the second noise
for?

Casca

Why,
for that
too.

Cassius

They
shouted thrice.  What was the last cry
for?

Casca

Why
for that
too.

Brutus

Was
the crown offered him
thrice?

Casca

Ay,
marry, was't, and he put it by thrice. .
.

So, though, during the time
that Brutus and Cassius are alone onstage, Brutus only remarks upon two shouts, Casca
confirms that there were three, and they were all in relation to Caesar's  being offered
and refusing of the crown.

As Casca tells the story, the
shouts happen in this way:

readability="7">

. . .the rabblement hooted and clapped their
chopped hands and threw up their sweaty night-caps and uttered such a deal of stinking
breath because Caesar refused the crown that it had almost choked Caesar. .
.

However, we cannot assume
the nature of these shouts simply by reading the play.  What sort of "shouts" they are
would be something each production of the play would decide.  Are the shouts Caesar's
supporters?  Detractors?  Some of each?  The script cannot really confirm this, since we
only have Casca's re-telling of the events to inform us, and he is hardly a
disinterested bystander.

So, in answer to your question,
whether all three shouts are the same or are each of a different kind of response, is
not something that reading the script alone can confirm.  This sort of information must
be gained from experiencing the play as Shakespeare meant it to be experienced -- as a
live performance.

For more on this scene, please follow the
links below.