How to add texture in onGUI()

I have made a working health bar that takes damage and regenerates over time, using two GUI rectangles. However, since the colors are only green when health is > 50% and red when health is <50%.I'm confused on how I would add texture to the health bars? How would I make the texture and implement it and make sure it works?

Here's the code

 // draw the health bar
         //draw the background:
         if(gameObject.GetComponent<Status> ().health > 50.0f) {
             InitStyles (Color.green);
         } else {
             InitStyles(Color.red);
         }
         GUI.BeginGroup(new Rect(pos.x, pos.y, size.x, size.y));
         GUI.Box(new Rect(0,0, size.x, size.y), emptyTex);
         
         //draw the filled-in part:
         GUI.BeginGroup(new Rect(0,0, gameObject.GetComponent<Status> ().health, size.y));//gameObject.GetComponent<Status> ().health?
         GUI.Box(new Rect(0,0, size.x, size.y), fullTex, currentStyle);
         GUI.EndGroup();
         GUI.EndGroup();
         
         // draw the mana bar
         //draw the background:
         InitStyles (Color.blue);
         GUI.BeginGroup(new Rect(pos.x, pos.y + size.y, size.x, size.y));
         GUI.Box(new Rect(0,0, size.x, size.y), emptyTex);
         
         //draw the filled-in part:
         GUI.BeginGroup(new Rect(0,0, gameObject.GetComponent<Status> ().mana, size.y));//gameObject.GetComponent<Status> ().health?
         GUI.Box(new Rect(0,0, size.x, size.y), fullTex, currentStyle);
         GUI.EndGroup();
         GUI.EndGroup();
         
         // draw the stamina (rage) bar
         //draw the background:
         InitStyles (Color.magenta);
         GUI.BeginGroup(new Rect(pos.x, pos.y + 2 * size.y, size.x, size.y));
         GUI.Box(new Rect(0,0, size.x, size.y), emptyTex);
         
         //draw the filled-in part:
         GUI.BeginGroup(new Rect(0,0, gameObject.GetComponent<Status> ().rage, size.y));//gameObject.GetComponent<Status> ().health?
         GUI.Box(new Rect(0,0, size.x, size.y), fullTex, currentStyle);
         GUI.EndGroup();
         GUI.EndGroup();
 
     private void InitStyles(Color c)
     {
         //if (currentStyle == null) {
             currentStyle = new GUIStyle (GUI.skin.box);
             currentStyle.normal.background = MakeTex (2, 2, c);
         //}
     }
     private Texture2D MakeTex( int width, int height, Color col )
     {
         Color[] pix = new Color[width * height];
         for( int i = 0; i < pix.Length; ++i )
         {
             pix[ i ] = col;
         }
         Texture2D result = new Texture2D( width, height );
         result.SetPixels( pix );
         result.Apply();
         return result;
     }