hi,
a revolute joint can be static ( like a nail pinned on a wall ) or moving (like a car and its rotating wheels)

static revolute joint:

  1. create 1 body (square, circle, image or text) ,
  2. create the revolute joint on the body you just created,
  3. adjust positions of body and/or revolute joint ( they'll remain connected even if not overlapping)
  4. press play !

moving revolute joint:

  1. create 2 overlapping bodies (square, circle, image or text) ,
  2. create the revolute joint on the overlapping area
  3. adjust positions...
  4. press play !

Revolute joint can be a rotating motor: check the "specific" parameters.

:)