You can get to the connector through view > connector.
On a page when you click on or inside an element like a dataview or listview it will show the entities or attributes that you can use.
What are you trying to achieve in which situation?
If you are using Studio (online IDE) then there isn’t a connector pane.
Using Studio Pro (local IDE) then see answer of Maarten.
Are you running through a online learning path? then probably you are using Studio instead of Studio Pro which you need to use.