How do i assign a Particle System to a variable?

I thinks it is probably pretty simple,but i don’t know how to do it.
I have a particle system and i have a particle system variable.
I want to assign the particle system to the variable at the start() method.

For example,for my MainPlayer game object i simple use:

 MainPlayer = GameObject.FindGameObjectWithTag("MainPlayer");

I want to do EXACTLY the same thing,but with my particle system.

If you have a reference to a GameObject, you can use .GetComponent<ParticleSystem>() to obtain a reference to the ParticleSystem it might have.

The same goes for every other Component you could conceivably install on a GameObject.