Map layers are accessed in the Layers page of the Information Panel. Switch to this page using the icons at the bottom of the panel:

Data layers are organised in to themes to assist in locating them - below, we see the Fauna and Flora theme and the expanded Fire theme and it's sub-themes.

 

Expand themes by clicking on them.

Toggle layers on and off using the tick box - you will need to toggle on the theme/sub-theme before toggling layers.

Some layers have a radio (round) check boxes - in this case, you will only be able turn on one layer at a time in that sub-list.

 Some layers are only visible at limited scales (to avoid cluttering the map). This is indicated by a layer name greyed-out (e.g. Fire Frequency). Zoom to the visible scale of a layer by using Layer Actions (below).

The transparency of some themes can be adjusted using the slide bar.

 Layer actions can be accessed by clicking the arrow to the right of the file name. Current actions are 'Zoom to full extent' and 'Zoom to visible scale'.

 View legend for a layer by expanding the legend icon on available layers.