Scoreboard is a pretty simple app. It has a few rows, each of which have the same elements. On the left, there's a blinking pink line. Tapping on that will let you put in a player's name, should you so choose. Next to that is a white space to keep track of that players score. Tapping the white space will add the score in the bottom left corner to that player's score. The down arrow decreases to the bid, the blank space keeps track of the bid, and the up arrow increases the bid. The bid space can be used to keep track of things like bids in games like Oh Joy or Wizard, or phases in Phase 10, or holes in Golf (the card game, although it could probably be used for the actual physical activity in dire circumstances).
Down on the bottom, there's numbers for entering in the score you need to add to the player. The box to the left displays the score to be added. Under that, there's a minus button in case you need to subtract from a score (enter in the score, then push the minus button to make it negative). The clr button is in case you make a mistake. It will erase the score in the bottom left box.
For example, say Alice, Bob, Claire, and Daniel are playing a game. Alice scores 3, so press 3 on the bottom square, and then white square beside Alice's name. Bob scores -2, so press the 2 button, then the minus button to turn it negative, then the white square beside Bob's name. Claire scores 13, but you accidentally pressed 30 instead. Just press clr, 13, then the white square beside Claire's name.
The clear bids button will reset all the bids to zero, which is handy for games like Oh Joy and Wizard, and probably shouldn't be used for Golf or Phase 10. The Reset Scores button will reset all scores and bids to zero and pop up a little message saying who got the highest score. Reset All will erase the names, scores, and bids, so you can play a new game with new friends. Load will load up the previous game you played, in case it got interrupted.