How do I swap gameObjects on a list by clicking in the UI?

I'm making a game where the player moves a certain piece by rearranging "movement cards" in order to create the path he wants the piece to take to reach the end goal. The problem is, I don't know how to do the rearranging part.

Currently, I have a UI element that has a fixed amount of Images that change sprite according to the list information and are given a random order and I'd like to know how I could make the player rearrange said pieces by clicking or dragging on the images and swapping them with the other images [example in the image]. (Swap those two pieces) Here's the code I have right now, and I honestly have no idea where to go from here. I'm very new to programming and I've been teaching myself only through experimenting so please don't go too hard on me :P

 void DarPeçasNecessarias() //Gives the exact amount of necessary pieces to finish the level
     {
         if (direçao.x > 0)
         {
             numRight = (int) direçao.x;
             for (int i = 0; i < numRight; i++)
             {
                 Peçass.Add("Right");
             }
             if (direçao.y > 0)
             {
                 numUp = (int) direçao.y;
                 for (int i = numRight; i < numRight + numUp; i++)
                 {
                     Peçass.Add("Up");
                 }
             }
             else if (direçao.y < 0)
             {
                 numDwn = (int) - direçao.y;
                 for (int i = numRight; i < numRight + numDwn; i++)
                 {
                     Peçass.Add("Down");
                 }
             }
             else { numDwn = 0; numUp = 0; }
 
         }
         else if (direçao.x < 0)
         {
             numLft = (int) - direçao.x;
             for (int i = 0; i < numLft; i++)
             {
                 Peçass.Add("Left");
             }
             if (direçao.y > 0)
             {
                 numUp = (int) direçao.y;
                 for (int i = numLft; i < numLft + numUp; i++)
                 {
                     Peçass.Add("Up");
                 }
             }
             else if (direçao.y < 0)
             {
                 numDwn = (int) - direçao.y;
                 for (int i = numLft; i < numLft + numDwn; i++)
                 {
                     Peçass.Add("Down");
                 }
             }
             else { numDwn = 0; numUp = 0; }
         }
         else { numLft = 0; numRight = 0; }
         //-----------------
         numPeçasNecessarias = numRight + numLft + numUp + numDwn;
         DarPeçasExtra();
     }
 
     void DarPeçasExtra() //Gives extra pieces
     {
         for (int i = numPeçasNecessarias; i < NumPeças; i++)
         {
             int nrg = Random.Range(1,5);
             //Debug.Log(nrg);
             if (nrg == 1)
             {
                 Peçass.Add("Up");
                 numUp++;
             }
             else if (nrg == 2)
             {
                 Peçass.Add("Down");
                 numDwn++;
             }
             else if (nrg == 3)
             {
                 Peçass.Add("Left");
                 numLft++;
             }
             else
             {
                 Peçass.Add("Right");
                 numRight++;
             }
         }
 
         ShuffleList();
     }
 
     void ShuffleList() //Shuffles the List
     {
         string Temp = "Temp";
         for (int i = 0; i < Peçass.Count; i++)
         {
             int rnd = Random.Range(0, Peçass.Count);
             Temp = Peçass[rnd];
             Peçass[rnd] = Peçass[i];
             Peçass[i] = Temp;
         }
         FillImages(); 
     }
 
     private void Update()
     {
         if (Input.GetKeyDown(KeyCode.P))
         {
             canMove = !canMove;
         }
 
         if (canMove)
         {
             if (!isRunning)
             {
                 StartCoroutine(AplicarMovimento());
             }
             
         }else { StopCoroutine(AplicarMovimento()); isRunning = false; }
 
         AbrirHotbar();
         FillImages();
     }
 
     void AbrirHotbar()//Opens the "hotbar" where all the movement cards are located
     {  
         if (Input.GetMouseButtonDown(0))
         {
             Vector3 mousePos = Camera.main.ScreenToWorldPoint(Input.mousePosition);
             Vector2 mousePos2D = new Vector2(mousePos.x, mousePos.y);
             RaycastHit2D hit = Physics2D.Raycast(mousePos2D, Vector2.zero);
 
             if (hit.transform.gameObject.CompareTag("TilePeça") && !Hotbar.activeSelf)
             {
                 Hotbar.SetActive(true);
             }
             else if (hit.transform.gameObject.CompareTag("TilePeça") && Hotbar.activeSelf)
             {
                 Hotbar.SetActive(false);
             }
         }
     } 
 
     void FillImages() // Changes the sprite of the images in the Hotbar
     {
         for (int i = 0; i < Peçass.Count; i++)
         {
             Transform botao = Hotbar.transform.GetChild(i);
             
             if (Peçass[i] == "Up")
             {
                 botao.GetComponent<Image>().sprite = Up;
             }else if (Peçass[i] == "Down")
             {
                 botao.GetComponent<Image>().sprite = Down;
             }
             else if (Peçass[i] == "Left")
             {
                 botao.GetComponent<Image>().sprite = Left;
             }
             else if (Peçass[i] == "Right")
             {
                 botao.GetComponent<Image>().sprite = Right;
             }
         }
     }