In the map, start by browsing the layers tabs in the upper right-hand corner of the map, on the yellow bar. You can see all the available layers by clicking the "All Layers" tab in the in the upper right-hand corner. Look for the globe icon—that's the All Layers tab.
To find a layer, scroll through the list or search (click on the magnifying glass to the right of the "Layers" header in the white pan).
To turn a layer on or off, click the check box to the left of the layer.
To see how the layer is represented on the map (e.g., is it an icon? a colored line?), click the down arrow to the left of the checkmark.
To declutter the map, turn off the default layers.