If you wish to move any of the elements, then make sure the main group folder is selected.
For example if you want to move the 4 x 9 paper then select the main ‘4 x 9’ group. This is to make sure that all the layers are selected so that everything such as shadows get moved at once.
Select the Move Tool in Photoshop in the panel on the left hand side. Press CMD + T (Mac) or CTRL + T (PC) and then move it by clicking and holding the mouse and then moving it to its new position.
As this scene creator is made to showcase paper leaning against a wall, the papers will need to be positioned so that the corner of the shadow lines up with the join of the wall and floor.
The image below shows the paper on the left in the correct position along the wall as the corner of the shadow lines up with the floor and wall join. The paper on the right is clearly in the wrong position and needs to be moved back toward the floor/wall join.
If you wish to layer the papers so that they overlap then you will need to position the paper so that the shadows line up correctly. You will need to move the front paper so that the corner of the shadow lines up with the bottom of the paper as shown below.