Please check it. do I need to add anything else ?

Of course you need I mean the san and BG its to plain maybe more color like a sand storm in the BG and less white color on the sand and more contexture

Well, maybe not sandstorm. But you'll definitely need to rework the sand - it looks like you took it from a scan or screenshot, and resized it up - it's heavily artifacted and of poor image quality. Not to mention that you extracted it probably with the polygon mask, hence the pixelated straight edges. The easiest way is probably to vector it - get curve of the horizon right, then a gradient fill will suffice. If you'd vectored Yotsuba, the elephant and the tree, that shouldn't be a problem.

The shadow of the tree is wrong, compared to the elephant shadow; The sun looks to be directly overhead, so the shadow should be of the foliage only. Go look at some trees at noontime - the shadows don't look like that.

Cure concept, good luck!