Beginner Help

I am a beginner, and have almost no experience with audio and arduino. I thought I could start with this shield, but there is so little information on the net that i cant get to do anything. With the sample code i managed to record and play. I cant take it any further though.
Can someone please help to understand the concept of an audio shield.
A few questions on my mind are:

  • lets say im using the tone() command and create a sound, how do i tell the arduino to send the signal to the output of the audio shield?
  • how could i expand the memory? how can i add an sd card for example?
  • how does a simple sketch look like when i want to read a sensor and play an audio file according to the reading of the sensor?
    please help, i cant find any infos anywhere about using this product.