Tournaments come in all shapes and sizes, using a variety of methods to determine a champion in a given age group. One of the most common arrangements is 'group play' followed by single elimination. In group play, teams play 2-3 matches against other teams in their group. Teams usually earn 3 points for a win and 1 for a draw. The results from group play then determine which teams from the group advance to the single elimination stage, which will usually be the semi-finals or even the championship final. Sometimes a consolation match is held to give teams that didn't advance their 3rd match (most tournaments guarantee teams a minimum number of matches, regardless of how they do - usually 3). In single elimination, a tie score usually results in a penalty kick shootout (kicks from the mark).
Another common structure is to crown a champion based on points. For example, if a division had 5 teams, they would schedule each team to play each other once (4 matches), and crown a champion based on points (usually 3 for a win and 1 for a draw). Tie breaker rules are used to resolve ties in the standings and vary widely by tournament. They can include head to head results, goal allowed, goal differential (usually limited to discourage coaches from running up scores), bonus points for shut-outs, kicks from the mark, and coin tosses.
You will often find that tournaments will rarely use the same structure for every division and instead choose a structure based on how many teams are in each division.