It depends on the specific bend, some are slow bends where you pick the string and slowly bend it, whereas some are fast where you pick and instantly bend it. In RS2014 it's quite visual, if you're playing RS1 than I'd suggest you change to RS2014 where it is much easier to see how the bends are supposed to be performed. You can also see how much you're supposed to bend with the up-arrows, if it's one arrow it's a half-step bend meaning you bend it only a little. Two arrows is a full-step bend and so on...