Toggle to the top, center of the page, and find Relations.

The Relations library is organized the same as with Types, but your icons are a bit different.
Clicking on a Relation here will give you the choice to install to your library.
Create a new Relation by clicking the bar in the middle.
Moving over to My relations is where you can see the objects in which you have attached to each Relation.
When you click on a specific Relation you are prompted with a set view of the details of the other objects which are linked.