Please help me word a suitable introduction and conclusion for Macbeth that can be used for most answers.Avoid the basics like its a play...

Since you have tagged your question with the terms
"ambition" and "downfall," a logical point of attack would be the play as a tragedy,
with a tragic hero whose actions lead to his own downfall.  In this play, it is often
argued that Macbeth is the tragic hero and "ambition" is often cited as his tragic flaw,
a character trait that leads to his downfall.

There is
however, a small problem with your question.  Though the introduction of an essay should
make clear the general topic -- in this case I am guessing
that the topic is discussion of the tragic hero and his downfall as prompted by a tragic
flaw -- it must also contain a thesis
statement.

And here is where the problem
with your question comes in.  There is no such thing as an introduction that can be
"used for most answers."  The introduction's primary purpose is to alert the reader to
the thesis statement that the essay will argue.  So, your introduction and your
conclusion must refer to this thesis statement specifically and cannot be catchall
paragraphs.

Again, using your tags as clues for the
direction you would like to take, I would suggest that you describe your topic as the
tragic hero -- the main character of a tragedy whose actions lead to his own downfall. 
Of course, then you must create a thesis statement, in which you state which character
you intend to argue is the hero of the play and what the flaw of the character is that
leads to his/her downfall.  As I mentioned above, your tags suggest that the flaw is
"ambition."

In creating the essay, again, there is no
general way to word a conclusion.  Its function is to restate your thesis and provide a
final summation of your point of view.  I have provided some links below, both in
reference to essay structure in general and the topic of the tragic
hero.