Perhaps a scientific approach would help the learning process... Strings vibrate when they are plucked... the pickups turn the vibration into electrical energy and your amp converts that to sound... The looser the string the bigger the eliptical path of the string... causing the tone to be deeper... (low frequencies) the tighter the string... the tighter the eliptical pattern and higher the pitch (high frequencies) By bending a string you are taking a normally tuned string and essentially adding tension to it by pushing upward or pulling downward on the string... This makes the strings lenght from bridge to the fretted point longer... which makes the string tension tighter... causing the note to seem sharpened. depending on the guage strings and hand strength you can bend up as high as a step and a half to 2 steps... string breakage is likely... haha. But a "step" is essentially 2 frets. A good way to practice bends is to fret at, for example... the 5th fret on the b string... the pluck the note and bend it up. Then pluck the 7th fret. Then pluck and bend the 5th fret to match the 7th fret note... you can do this anywhere on the fretboard to practice...