If your on the low E string youd have to bend down or you'll fret out right off the fretboard obviously. Bend up or down when on middle strings and up on the bottom strings or again you'll fret out.

You can anchor your hand against the neck and bend with your wrist or bend with your fingers only. For vibrato you can bend the strings or shake your fingers back and forth on the strings it's really up to what works for you. Although a shake type of vibrato works best on top or bottom string or again youll fret out.

Use all your fingers to reinforce the bend. (when on the 2nd fret for instance I will place two fingers in between frets to reinforce the bend) There really is no right or wrong way and everyones bend or vibrato is different. You can bend the strings or shake your fingers back and forth on the strings it's really up to what works for you.

:)