Fantasy points are calculated by managing your lineup to maximize your game opportunities for each position and player in a given week.
You can find more details on navigating the Lineup screen and managing lineups at the following links.
Your final score will be the total of points earned for the players which you choose to remain activated for their games in that week.
Should you choose not to manage your lineup, and are over your available game opportunities, the points will be counted based on the order of the schedule until maximum opportunities for the week have been reached.
Meaning, if you are allowed 4 game opportunities for the week, but have 8 scheduled games, the first 4 games played would have their points counted.
If you are wanting later games to count towards your final score, you would have to choose which player to bench for games earlier in the week.
In the event you have 2 scheduled games left for a position that has only 1 opportunity available, and both games start at the same time, the game whose player was projected the highest would be counted.