Open Plug-in Manager

Go toTools | Plug-in Manager.

If there is a “+” sign to the left of the plug-in type on the tree view, then there are already downloaded plug-ins related to that type. You can select any of them, and configure their settings.

If there is not a "+" sign next to the plug-in type on the tree view, you have no plug-ins of that type. You can either download some, or add a plug-in you already have on your computer.