Go to your project and the API connections page from the Project menu.
Click "New Api" and choose the type of service you want to connect to.
This will request the authentication credentials that the currently selected service requires. You can usually get this information from their admin area.
This will also display any configuration options available for that service.
Make sure you set the api to "Active".
Then click
Uncheck the "Active" checkbox if you ever need to disable the connection to this service.