The Assignments panel is positioned on the bottom left corner alongside Attributes and Occurrences. 

The Assignments panel shows you the models which the selected model or object is currently linked to. 

In the same panel, there are options for linking a model. On the bottom of the panel, there are two links, which when clicked open a new popup for creating a link to a new model or linking an existing model.

The Popup that appears is the same as when you want to Create a new model in a selected folder on the Explorer tab. 

The difference is that a default name is set to match the selected model/object and two check-boxes on the bottom of the popup: 

1. Open model after creation - Check if you want to open your model after you finish giving a name and selecting model type. Click Save button and you will be redirected to a newly created model.
2. Create object occurrence - Check if you want to create an occurrence of the assigned object in the selected model. This is explained in the Occurrences section.

When you have filled in all the required fields and selected a type of a model, click Save to finish.

The second button is to link a model/object to an existing model. When clicked, a popup shows where you can choose a model to link with.