Creating Dropdown menue for variables in the Inspector using C#

Hi , I am trying to get create a dropdown menue for my variables to get something like

Hero stats:-hp -mp ... Gear stats:-weapon damage -dmg reduction ...

The thing is that I already have a tons of variable to play with but I need to add at least 300 more as I am making a reference script that contains all the variables for my hero. So I need to make some order in there .

Ive read about the possibility of creating a dropdown as the clickable arrows in the inspector (we see it in many scrips that comes with unity) and that is what I look for.

After many tryes I still cant get this to work and everytime I read a post they aren't using the same procedure at all. This get verry confusing.

Here is the script I have so far , it displays a couple variables and they are divided in the class I would like.

 using UnityEngine;
 using System.Collections;
 public class Test : MonoBehaviour
 
 {
     //All the booleans that declare a state like : hero is fighting
     public bool isFighting = false;
     public bool isInAction = false;
     public bool isTakingDamage = false;
     public bool isDead = false;
     public bool isLevelingUp = false;
     public bool isSettingLevelUp =false;
 
     //The hero stats example : the Hero health points
     public int healthPoints = 100;
     public int manaPoints = 100;
     public int spellEfficiency = 3;
     public int meleeEfficiency = 3;
     public int dodgePercent = 3;
     public int blockPercent = 3;
     public int level = 1;
     public int actualXP = 100;
     public int neededXP = 1000;
     public int money = 0;
 
     //The hero GEAR stats , example : The hero weapon damage
     public int weaponDamage = 5;
     public int weaponSpellDamage = 0;
     public int meleeDamageReduction = 0;
     public int spellDamageReduction = 0;
 
     //Elemental resistances , example : Lightning damage reduction in percent
     public int lightningReduction = 0;
     public int fireReduction = 0;
     public int iceReduction = 0;
     public int chaosReduction = 0;
     public int lightReduction = 0;
     public int massReduction = 0;
 
 }