Appearing slide info when touch guiTexture Button

Hy,could somebody help me? I'm new for unity. Im using GUI texture for my button with the normal an hover condition. Now I want to make like this, when I touch the button, my slide show will appear. I have make the slide box, but i dont know how to make it appear on screen.. I guess i have to make void update? can some tell me how ? In C# please :) Thanks

 void OnGUI(){
         if (show == true) {
             GUI.BeginGroup (new Rect (Screen.width / 2 - 200, Screen.height / 2 - 250, 800, 500));
             GUI.Box (new Rect (0, 50, 405, 360), "Informasi Objek");
             
             scrollPosition1 = GUI.BeginScrollView(new Rect(30,0,350,390),scrollPosition1,new Rect(0,0,1150,200));
             
             GUI.DrawTexture(new Rect(0,90,350,210),gambar1);
             GUI.Label(new Rect(0,300,350,80),info1);
             
             
             GUI.DrawTexture(new Rect(400,90,350,210),gambar2);
             GUI.Label(new Rect(400,300,350,80),info2);
             
             GUI.DrawTexture(new Rect(800,90,350,210),gambar3);
             GUI.Label(new Rect(800,300,350,80),info3);
             
             
             GUI.EndScrollView();
             GUI.EndGroup();
         }