Daily Fantasy Sports (DFS) is an accelerated version of Fantasy Sports.
In DFS, contests are played between contestants that compete on who can create the best lineup of real players from professional sports. Each player is assigned a dollar value based on their skill level, with the higher skilled players having a higher dollar amount and the lower skilled players having a lower dollar amount. For each contest, contestants must pick 8 players plus 1 team's Defense & Special Teams, with the total dollar value of all of the players fitting within the salary cap of $50,000. So you can't just load up on all of the top players -- you need to be strategic about it!
Then as players that you choose play in the games scheduled for that date/time, they'll accumulate points for your contest entry based on their performance. Add up all of the points that everyone in your lineup has, and that will be your total "score" for that contest. The higher the score, the higher your place, the more you can win.
Each DFS contest is always based on games for one specific date/time time slot. You can't mix and match games from different time slots for the same contest. For example, you could create or join a DFS contest for all of the NFL games played on September 27th at 1:05pm Pacific Time, but any games slated for September 27th at 1:25pm Pacific Time would need to be for a different contest, not the same one as the games at 1:05pm.
**NOTE: ZenSports currently only offers DFS contests for NFL games. We'll be looking to add DFS contests for other leagues and sports in the very near future.