Today's session will begin with a listing of the 17 editing instruments that come "stock" with Apple's Garageband.

Adding and Adjusting Effects

Each Real Instrument has a set of effects, which include a noise gate, compression, equalization (EQ), echo, and reverb. You can adjust a track's effects, and add up to four additional effects. 
Most of these are found in newer systems and more recent versions of GB:
Amp Simulation
Auto Wah
Automatic Filter
Bass Amp 
Bass Reduction
Bitcrusher
Chorus
Distortion
Flanger
Overdrive
Phaser
Speech Enhancer
Track Echo
Track Reverb
Treble Reduction
Tremolo
Vocal Transformer,
 all are listed in the Track Info window. 

I will go through each one seperately but the real way to learn it is to start GB and edit your own instruments!!!