How to use FB.Feed (not FB.API) in sharing a screenshot in picture parameter?

I made it :) btw I am a newbie about Unity and C# also. So i am not sure this is best way or not

Anyway FB.API use wwwForm so I made own input form with wwwForm like below and use FB.API

 private IEnumerator TakeScreenshot()
 {
     yield return new WaitForEndOfFrame();
     
     var width = Screen.width;
     var height = Screen.height;
     var tex = new Texture2D(width, height, TextureFormat.RGB24, false);
     // Read screen contents into the texture
     tex.ReadPixels(new Rect(0, 0, width, height), 0, 0);
     tex.Apply();
     byte[] screenshot = tex.EncodeToPNG();

            //screenShottexture is Texture to another Image of own GUI
     screenShot.texture = tex;

     var wwwForm = new WWWForm();
     wwwForm.AddBinaryData("image", screenshot, "intotheblack.png");

             // screenWWWForm is private variable to own GUI
     screenWWWForm = wwwForm;

            // this is my own GUI panel. (I am using 4.6 new GUI
     screenShotPanel.SetActive(true);

// I didn't call FB.API on this Fuction. I call it from my own GUI;

// FB.API("me/photos", Facebook.HttpMethod.POST, Callback, wwwForm); }

Anyway my idea is draw tex on another GUI RawImage, so user can check image and type other input form. and upload;