Transforming an item is very useful for proper arrangement and proportions in your scene. Transformations may include:
Select your item’s layer group and use Move Tool to move the whole group around.
Select your item’s layer group, enter Free Transform mode by clicking Ctrl-T (Command-T), find the rotation mode by slightly moving away from the item, and rotate freely as neccessary.
Select your item’s layer group or smart object group (advised), enter Free Transform mode by clicking Ctrl-T (Command-T) and by holding the Shift key, grab any corner anchor to resize the group. Holding the Shift key assures the item’s proportions don’t change.
An item is composed by several layers (object itself, shadows etc), therefore it is important to perform transformation over the whole group of layers of a given item.