What is the summary of Shakespeare's As You Like It, Act I, scene i?

The opening scene is called the Exposition Scene. The
scene is of great importance as it gives a clear insight into the characters,the theme
and the plot of the play.

The introductory scene highlights
the folowing aspects of the play:

a) The enmity between
Orlando and Oliver with respect to the will of Late Sir Rowland de
Boys.

b) The enmity between Duke Ferdinand and Duke
Frederick (Theme of usurpation)

c) The sisterly love
between Rosalind and Celia.

The scene opens with Orlando
discussing and complaining to Adam how his own elder brother Oliver has treated him very
unkindly, kept him like a rustic, not given him thousand crowns bequeathed by his
father, not provided him education and taking away from him the qualities that he had by
birth. He also informs that the spirit of his father revolts against this
servitude.

When Oliver enters, there is a verbal spat
between them, both accusing each other. Oliver asks Orlando what he was doing there and
that he must leave the place. Orlando tells his brother that even if there were 20
brothers between them it did not take away from Orlando the right that he was as
high-born as was his brother. The moment Oliver calls him a villain and slaps him on the
back, the latter holds him by the throat and vows to release him only when he gets his
due share. Adam is also ill-treated in this fight.

A little
later, Charles enters and we come to know that there is no new news but that old duke
has been banished, and three or four Lords have voluntarily decided to be with him in
the Forest of Arden. However, Rosalind and Celia are together for the Duke Junior
detained Rosalind for the sake of Celia. The duke Senior lives in the Forest like 
Little Robin Hood and helped people.

Charles, then, 
informs that he had heard Orlando was planning to fight him in a disguised  form. He
requests Oliver to  dissuade Orlando from fighting as he was fighting for his reputation
and will not leave anyone unharmed. It was for the sake of Oliver that he had come,but
if the young man did not comply, it would not be Charles'
fault.

Oliver senses a great opportunity to eliminate
Orlando. He instigates Charles by telling him that Orlando was the stubbornest fellow in
France and was always jealous of other people. He also tells Charles that Orlando will
employ every means to harm him and so he must not think of breaking his fingers but
could break his neck as well.

We finally come to hear the
soliloquy of Oliver giving reasons for his extreme hatred of his brother and how he
plans to instigate his brother to this fight.

Thus the
 first scene acts as  a curtain raiser to the play.