Cut out the glass thingy. Select the channel with the best contrast and copy it. Apply a levels adjustment and CTRL click on the thumbnail of the copied channel to make a selection.
Deactivate the channel, and active RGB and go back to layers. Whith the selection still active, press delete and if all went well the glass is now transparent but still 'glassy'
Fit the mask to the woman. The angles are quite good. A slight adjustment was needed on the top strap. I masked out bit of the straps to make the hair fall over.
Add shadow to the woman. All shadow layers where set to multiply, and around 75% fill. Both have 3 layers of shadow. The contact shadow on the ground, the general shadow and the cast shadow.
I added noise on the background layers. On top of that a levels adjustment to make it look like stars, with a little blue in there to make it more realistic.