Click 
to create child-parent relationships between the actors. You can also achieve this by dragging actors into assemblies in the Assembly tree.
Note:
A child can have only one parent but a parent can have multiple children.
Click
and
pivot alignment tools to align each child-parent group's pivots.
Note:
For kinematic motions to work, a child's pivot must be in the same alignment as its parent's pivot, and all pivots in a chain of child-parent relationships must be aligned in the same direction. The child pivot location determines where the link is applied and the parent pivot location determines the link orientation and movement. For example, all pivots could have the Z direction pointing up or down. Use
Align Pivots to copy pivot alignment between specified actors.
In the Properties pane for a selected child or parent, assign the appropriate
Link type (such as
Free or
Linear) and the axis.
Select
Show/Hide Degrees of Freedom to see the direction of motion.
Optionally, select
Limited joints and specify motion limits.
Select
Kinematic Free Dragging and drag the actors to visualize their motions.