And Spherize filter in Filter > Distort menu box.
The layer must be selected.

Christmas Wallpaper or Background

I suggest you to spherize the image several times.

Christmas Wallpaper or Background

Plus to that change the blending mode to Luminously and opacity level to about 79%-75%.

You can also erase a little bit ob the image to blend the edges.

Christmas Wallpaper or Background

And here we go. This was the first step. Now do the same thing create 2nd clipping mask with the same image.

Christmas Wallpaper or Background

And round 3 ? the 3rd clipping mask.

Play with opacity and layer modes as well.

paint over
  
it (on a new separate layer) to accent the ball roundness. Spotlights ? with white and shadows with dark blue. Well something like this.

Christmas Wallpaper or Background

Here is our current layer order. You can see 3 clipping masks. If you're confident in your result just link the 3 clipping masks and you source layer and merge them into 1 single layer.

Christmas Wallpaper or Background



Christmas Wallpaper or Background



Christmas Wallpaper or Background

Create a copy of the big ball layer. We will need it to create a reflection in the smaller ball. So watch.

Christmas Wallpaper or Background