Add the background now.



Open the necessary picture in a new window. Mark it out with Rectangular Marquee Tool, copy it: Edit - Copy (ctrl+c) and get back to the processed picture to insert the background on a new layer: Edit - Paste (ctrl+v). Move this layer on the bottom. Applying Magic Wand Tool, mark out the flowers.



Copy them and insert them on a new layer. The previous layer with the background must be decolorized. Apply to it also Photo Filter with Sepia nuance.
Get back now to the flowers' layer and change their color: Image - Adjustments - Hue/Saturation (ctrl+u)



Take now a photo representing a lion made of stone.



Cut it and insert it on a new layer also, under the girl's layer. Decolorize the layer now, applying Filter - Blur - Smart Blur, giving to it the Sepia nuance.



Copy now the girl's layer: Layer ??? Duplicate Layer, making the copy of grey color: Image ??? Adjustments ??? Brightness/Contrast



Give it also the Sepia nuance. Blur it out, applying Filter - Blur - Gaussian Blur. Place this layer under the girl's layer to get her shadow.



The Brush Tool can be useful in representing a more obvious shadow, from the girl's palm.