How do I update an image to all connected Players on a Multiplayer server?

Hello, I am currently working on a Multiplayer Game. As a part of this game, players can draw on an image I chose. For this i used this code:

using System.Collections.Generic; using UnityEngine; using System.Collections;

public class paint : MonoBehaviour { int i; int i2; Color c; float f;

 int sw;
 int sh;

 float mx;
 float my;

 int px;
 int py;

 //drop a texture into the inpector 
 //in the texture import settings you must set the type to "advanced"
 //and then set "read/write" to true!!!!!!!

 public Texture2D original;

 Texture2D myimage;

 public int brush;
 public int erase;
 int oldp;

 public Color drawcolor;
 private NetworkIdentity myimageID;



 void Start()
 {

     if (original == null) { original = new Texture2D(400, 300); }

     // change these next three variables to whatever you want!!!
     drawcolor = Color.white;
     brush = 1;
     erase = 20;

     //copy our original into our new paintable image 
     myimage = new Texture2D(original.width, original.height);

     i = original.width;
     while (i > 0)
     {
         i--;
         i2 = original.height;
         while (i2 > 0)
         {
             i2--;
             c = original.GetPixel(i, i2);
             myimage.SetPixel(i, i2, c);
         }
     }

     myimage.Apply();
     myimage.filterMode = FilterMode.Point;//<remove this if you want it more fuzzy

 }

 void OnGUI()
 {
     GUI.DrawTexture(new Rect(0, 0, Screen.width, Screen.height), myimage);
 }

 void Update()
 {


     sw = Screen.width;
     sh = Screen.height;

     mx = Input.mousePosition.x / sw;
     my = Input.mousePosition.y / sh;

     px = Mathf.RoundToInt(myimage.width * mx);
     py = Mathf.RoundToInt(myimage.height * my) - 1;


     if (px + py != oldp)
     {// <-- only draw when mouse moves for proficiency
         oldp = px + py;

         if (Input.GetMouseButton(0))
         {//------mouse right button  draws--------

             px += -Mathf.RoundToInt(brush * .5f);
             py += -Mathf.RoundToInt(brush * .5f);

             i = 0;
             while (i < brush)
             {
                 i++;//<--next two loops for brush size
                 i2 = 0;
                 while (i2 < brush)
                 {
                     i2++;
                     if (px + i > -1 && px + i < myimage.width)
                     {//<---dont try to draw off image width
                         if (py + i2 > -1 && py + i2 < myimage.height)
                         {//<---dont try to draw off image height

                             myimage.SetPixel(px + i, py + i2, drawcolor);


                         }
                     }
                 }
             }
             myimage.Apply();

         }


         if (Input.GetMouseButton(1))
         {//-----mouse left erases----

             px += -Mathf.RoundToInt(erase * .5f);
             py += -Mathf.RoundToInt(erase * .5f);

             i = 0;
             while (i < erase)
             {
                 i++;
                 i2 = 0;
                 while (i2 < erase)
                 {
                     i2++;
                     if (px + i > -1 && px + i < myimage.width)
                     {
                         if (py + i2 > -1 && py + i2 < myimage.height)
                         {

                             c = original.GetPixel(px + i, py + i2);//<--grab pixel from original for erasing
                             myimage.SetPixel(px + i, py + i2, c);


                         }
                     }
                 }
             }
             myimage.Apply();
         }
     }
 }  

}

This is all working fine, but only for every single Player, so the other Players can't see what one has drawn... As this is my first ever game i dont really know, how to fix this issue and update the drawings to all others players... I hope you understand my problem and can help me to solve it!