This game is available inside of your farmhouse. As you exit your house in the morning, turn around and immediately go back inside. If you time it correctly then the game time will be 6:01 am. You can confirm the time if you had purchased the Clock for your house.
When the time is 6:01 am you can play the Girl Select game. Walk over to the shelf that holds your records (in the bottom left-corner) and press the A button. You will then access the mini game.
This game will display 12 girls on the screen. You may (or may not) see Muffy, Flora, Celia, Nami, and Lumina. The girls will be facing various directions and there may be multiple copies of each girl. After a few moments the scene will go away and you will be asked a question about what you just saw.
You may be asked how many of X girl there are, or even how many girls were facing X direction. If you don't have a good short-term memory then this game can be challenging! Luckily you can "cheat" a little bit. On the scene where you view the 12 girls, simply press the Start button on your DS. The game will pause, allowing you to take longer to memorize their positions, or even write them down on a piece of paper. Then just press the Start button again to unpause your game and answer the question appropriately.
Each time you win, you will increase your Farm Degree a little bit.