To wheel you take the model on the edge of your formation and move it forwards in the direction you want to go. You do not need to move it the full movement distance if you don't want to. Having moved it to the new position you line the rest of the models up with it, leaving the model at the opposite end of the line to act as a pivot.

The entire unit counts as having moved as far as the outside model. Once you have wheeled you may use any movement the unit has left.

A unit can wheel several times during its move as long as it has movement left and is not charging.