This dialog is accessible from the Online Data Sources tool > Connections tab with the New, Copy and Modify buttons. The Connection Management panel contains the following controls:
Connection Management panel
Name: enter the name of the service
URL: enter the 'Get Capabilities' Address of the WMS service
Login name: enter the optional login name to access the service
Password: enter the optional password to access the service
Get List of Available Data Layers - queries the available data layers at the Server URL
Data Layers list: list the available WMS/WMTS/WFS data layers to select and define the background map layer. Multiple layers can be selected.
Cancel - closes the panel
Save - saves the entered parameters with the selected data layers in the list