[Parasite]

A sailboat's sail is shaped like an airplane wing on it's side. i.e. Sahara. The "Lift" produced by this can pull the sail boat through the water. You just must have a big bladed thing in the water to make sure you cannot go sideways, only forward. You head at an angle to the wind so it blows a little from the side to keep the sails "full" and in the shape of a wing.

A solar sail does not use this air pressure difference to move. I mean, it IS in space. But there is orbital speed. Without getting deep into orbital mechanics, if you slow down while in orbit you will tend to fall. If you speed up, you will tend to rise up and go in a wider orbit. If you angle the mirrors to reflect the light ahead, you will slow down and get closer to the sun.

The old way of thinking about solar sails is a lot like the old square sails of ships. They could only go with the wind and used the "Trade Winds" to travel that mainly blew in one direction. If we start talking about laser boosts to other star systems, this would be the way to think.