You can work with and arrange the objects on a sheet in a number of ways:
Layer (or stack) objects to create the appearance of depth
Group objects to more easily move, resize, or rotate them as a single unit
Lock objects to avoid inadvertently moving, modifying, or deleting them
Drag an object so that it overlaps with one or more other objects.
Tap 
, then tap Arrange.
Tap an object, then do one of the following:
Drag the slider until the object is layered where you want it.
Tap the icons to move the selected object forward or backward.
You can select multiple objects to layer them all at once.
Touch and hold an object, then with another finger tap the other objects you want to group.
Lift your fingers, then tap Group.
To ungroup objects, tap the group, then tap Ungroup.
When an object is locked, you can’t move, delete, or modify it in any way until you unlock it.
Tap an object to select it or select multiple objects.
Tap , tap Arrange, then tap Lock.
To unlock an object, tap it, then tap Unlock.