On any map, go to the map toolbar
Scroll through the layer list OR type in layer name in 'Filter layers' field to locate desired layer
Click on the desired layer to view the layer as an overlay on the map. The layer should activate once the layer is selected in the layers menu, but it may take a few seconds to load.
Dragdrop map layer pop-ups
Copy feature/copy to drawing
To view the layer source/read more info about a layer, click the source link to the right of the layer name: