In order to referee in Competitive games the referee must be 13 years old and certified with the state organization. Those interested in refereeing that are younger than 13 may start with games in the Recreational Program to get experience. To begin with Rec please contact Bob Enright at the email below.
There is a state organization named Rhode Island State Referee Committee (RISRC) that qualifies referees and operates the referee program in RI. So the first step is to go to their website which provides information on becoming a new referee. The steps involve taking a course from RISRC to become certified, entering the referee database for assignments, and notifying the WFFSC Referee Coordinator who currently is Bob Enright at firstname.lastname@example.org.
Once you are certified and in the system and on Bob's list then he will assign recreational games usually starting in U8 to get some experience. As the referee gains experience they will move to older age games and maybe eventually move to be assigned to competitive games.
Here is a document that explains the laws of the game: Soccer Laws Document