I need to know what Gain,Trebble and all those things do. I know that disortion gives rock and roll sound...thats about it.
gain adds more rock and roll sound. the higher the gain, the more distortion. treble, middle, and bass, are what people call tone control. This is if u want ur guitar to sound like a bass, have emphasis on the higher notes, lower notes, perfect balance, w.e u want. so to figure out wht they do, mess with the knobs, turn some to 0 some to ten to see the different sounds each makes
Your bass knob is gonna control the bass... So like the lows, or the rumble. Where as the treble will bring up the highs, or the ringing stuff. Mid will control the overall dynamics (this makes the sound appear as though it is behind a door and you are on the other side, or you have your head up against the amp). Mid is usually the last thing you touch and the sound that you are looking for out of this knob is entirely up to you.

Note: all amps will have different sounds depending on the knob settings.

Overall, when playing with knobs, the sound is totally up to you and is designed by ear (unless your beethoven).