The "height" (top/bottom) is how high or low the sound is.Tuners make playing sound better, but it'll also familiarize you with which string and fret combinations correspond with which notes. There should be one anywhere guitars or guitar music is sold. A useful mnemonic to remember the string arrangement is "Every BodyGets Dinner At Eight" (going from high E to low E) or "Eat AllDay Get Big Easy" (low to High). You should try to make up your own acronym, it will help you remember more easily. If you cannot afford a Tuner, you can also tune your guitar without one.
