Orbital Mechanics 1.02
Your craft is in motion & the sail pushes against the wind (plasma)/light (sails): hit it so the force pushes your sail in the direction of your orbital motion & the energy of your orbit increases (ie, you move outwards, slowing down in the process); do the opposite & the energy of your orbit decreases (ie, you move inwards, with increased velocity)... easy; although you have to be able to visualise a three dimensional space complete with multiple planes of motion. I said it was similar to tacking; but that wasn't meant to suggest that it was identical.
This flexibility is why sails (real; & virtual) have been recommended for all kinds of high delta v from large Mercury orbiters outwards.
Robert