In case you still want to load PNG images, I'll just leave this code snippet here:
public static Texture2D FromImage(BitmapImage image, GraphicsDevice device)
{
WriteableBitmap bitmap = new WriteableBitmap(image);
return FromImageData(bitmap.Pixels, bitmap.PixelWidth,
bitmap.PixelHeight, device);
}
public static Texture2D FromImageData(int[] data, int width, int height, GraphicsDevice device)
{
Texture2D texture = Texture2D.New(device, width, height,
PixelFormat.B8G8R8A8.UNorm);
texture.SetData<int>(data);
return texture;
}