Desaturate bottle and make it transparent. There are many tutorials for how to make something transparent.
Here are two for those who are unsure how to do it.
I did a rough sketch of a couple of people facing each other. This was simply to use a guide for my warping and shaping of the glass bottle. I deleted this layer once the glass was warped into shape.
Turned the bottle upside down, duplicated it, copied and pasted the top lip of the bottle to make the neck areas longer. Warped the bottle into face shapes using the puppet warp and liquify tools. Copied areas which I circled in different colors and placed where indicated to give some detail to eyes noses, mouths and ears.
Made my own background using a blue gradient fill and cloud brushes.
Placed background under transparent glass faces.
Using the smudge tool, I smudged the top of the heads where the bottom of the bottle was showing to give it the impression of some hair.
The flower petal shapes behind the heads are also done with brushes.
The merged copy was filtered with Topaz Glow.
This was duplicated a few times and layers were blended using subtract, multiply, screen and soft light. Masks were applied to various areas to lighten or darken them.
The finished art work was done using only the source image, photoshop tools and filters, cloud brushes from Brusheezy, and other brushes which are already in photoshop.