Depending on what you want to do,. it’s as easy as adding the force and adjusting the strength as required to create the effect you need.
Create a Particle emitter, add a direction Force, and enable (use forces of the scene) in the particle emitter (advanced tab) settings.
In this mode, the particles will also be effected by the scene Gravity,. so you’ll either need to adjust the particle emitter velocity to compensate for that,.. or, switch off the default scene gravity in the Physics panel. and replace it with a more controllable Directional Force, which you can adjust the strength of to suit the effect you want, and you can also key-frame the strength over time.
If you use Physics objects in the scene, you’ll need to Run the Physics simulation Before you’ll see any effect from Forces.
The Flow force will create turbulent wind like effects, for things like leaves blowing around.
the strength values of this can also be key-framed and you can use a Noise tweener, or Oscillate tweener to add more randomisation to it.
The Torque force will create a Rotational Spin force, and can work well with Physics objects, like a spinning top (toy)
Physics objects also react to collisions or Forces generated by animated objects, such as a figure kicking a physics ball.
The Point Force can be used to either Attract or Repel physics objects and particles.
It really depends on what you want to create , and then experimenting with the strength values of the forces.
Hope it helps