In this first part of Justice as Fairness: A Restatement, Rawls introduces a number of background concepts that his theory of justice relies on, but does not state the theory or any of his argument for the theory. Consequently, the discussion is rather dry and abstract, but the background is indeed necessary.
I suggest that you write out briefly what Rawls means by each of the following 12 phrases:
A fair system of cooperation
Citizens as fair and equal persons
A well-ordered society
A public conception of justice
A political conception of justice
The basic structure of society
The original position
The two moral powers of individuals
The equality of individuals
The freedom of individuals
A more difficult, but even more important task is then to figure out how these notions are related to one another.