How to post description when sharing screenshot using Facebook SDK plugin

Hi to all, I am currently doing a function that will share the screenshot of my app. I used Facebook SDK. sharing screenshot of my app works fine but I want to add a description with it. When I click the share button, a dialog should appear to enter description. How can I do that? Please help. Thank you.
Here’s my code below

IEnumerator TakeScreenShot()
    {  
      
        yield return new WaitForEndOfFrame();

        var width = Screen.width;
        var height = Screen.height;
        var text = new Texture2D(width, height, TextureFormat.RGB24, false);

        text.ReadPixels(new Rect(0, 0, width, height), 0, 0);
        text.Apply();

        byte[] screenshot = text.EncodeToPNG();
        var wwwForm = new WWWForm();
        wwwForm.AddBinaryData("image", screenshot, "share_image");
        FB.API("me/photos", HttpMethod.POST, Callback, wwwForm);
    
    }

FYI
For anyone who is looking for share screenshot to FB directly, please check the answer there.