How to assign GameObject used in a Custom Class?

Hello,

I am making a weapon switching script for my game. I have made a custom class here:

 public class WeaponManager : MonoBehaviour
 {
     public string type;
     public string name;
     public float damage;
     public float range;
     public int perClip;
     public int maxAmmo;
     public float fireRate;
     public float reloadTime;
 
     public GameObject weapon;  //weapon body
   
     public Transform bulletSpawn;
 
     public WeaponManager(string typ, string nam, float dmg, float rng, int pCl, int mxA, float frR, float rTm, GameObject wep, Transform blt)
     {
         type = typ;
         name = nam;
         damage = dmg;
         range = rng;
         perClip = pCl;
         maxAmmo = mxA;
         fireRate = frR;
         reloadTime = rTm;
         weapon = wep;
         bulletSpawn = blt;
     }

Now, I will create an object from this class.

 WeaponManager M16 = new WeaponManager("Rifle", "M16", 20, 200, 30, 180, 10, 1.5f,  
  GetComponent<GameObject>,  GetComponent<Transform>);

What I am trying to do when you see the

 GetComponent<GameObject>()

stuff is to assign a tangible object in Unity3D. I am trying to assign the weapon's body GameObject and the weapon's bullet spawn Transform created in the WeaponManager class for each new weapon created using the class.

I can't figure out how to get the little bar in the Unity Editor screens to pop up to drag a prefab into it.

A thank you in advance for those willing to help!