How to show instance variables in the inspector

I am trying to use a system of base and derived classes in Unity for the first time.

What I can't figure out is how I can show instance variables in the inspector, if that is possible at all. Possibly I'm doing this completely wrong from the start. My intention was to set up a system where I can have spells derive from the base class and build on them, and then use a script on the player to instantiate these attacks. So I don't need an entire, almost duplicate, script for each attack.

I need them in the inspector so that I can assign prefabs for, for example, particle systems that are specific to each attack.

This is the beginning that I've made:

 using UnityEngine;
 using System.Collections;
 
 
 public class AttacksHandler : MonoBehaviour
 {
     GameObject playerGO;
 
     public class Spell
     {
         public bool needsTarget;
         public float movementSpeed;
         public int damage;
         public GameObject attackVisual; //HOW TO SHOW THIS THING IN INSPECTOR FOR EACH INSTANCE?
 
         public Spell(bool _needsTarget, float _movementSpeed, int _damage)
         {
             needsTarget = _needsTarget;
             movementSpeed = _movementSpeed;
             damage = _damage;
         }
     }
 
     public class Fireball : Spell
     {
         public ParticleSystem explosionEffect; //HOW TO SHOW THIS THING IN INSPECTOR FOR EACH INSTANCE?
         GameObject target;
 
         public Fireball(bool _needsTarget, float _movementSpeed, int _damage) :
             base(_needsTarget, _movementSpeed, _damage)
         {
         }
     }
 
     public Fireball redFireball = new Fireball(true, 50f, 25);
     public Fireball greenFireball = new Fireball(false, 20f, 200);
 
     void Start()
     {
         playerGO = GameObject.FindGameObjectWithTag("Player");
     }
 }

Again, I may be doing this completely wrong alltogether but this was my idea to use OOP.