How to create an object with buttons and image attached?

I want to press on a button and create a prefab game object on which i attach an image and buttons. This is my code so far:

 public GameObject prefab;
 private GameObject myprop;
 
 `void OnGUI(){
 ...`
  if (GUILayout.Button("Propose")){
                     myprop=Instantiate(prefab,new Vector3(Screen.width/2,Screen.height/2,0) , Quaternion.identity)as GameObject;}
             

myprop GameObject has the following script where i create image and button

 void OnGUI(){
 GUILayout.BeginArea(new Rect(250,250,150,170));
     GUILayout.BeginVertical();
     GUILayout.Box (propIcon);
 
     if(GUILayout.Button("ok")){
             //do something
     }
 GUILayout.EndVertical();
 GUILayout.EndArea();
 }

i cannot see the prefab object on scene and also attached image and buttons dont appear attached on object but on other location. Does anyone know how to make this happen? Thank you in advance.