Normally, layer panel should be located just underneath the brush list:
However, on some of the devices there might not be enough space and the layer panel might not show up on the screen.
In that case, you should be able to make the layer panel visible by adjusting the layout. In order to do that, please click on the gear icon next to the color wheel to bring out the layout dropdown menu, and choose one of these options:
"Simple mode" - it will hide less advanced options from the interface and make more space for the layer list
"Two columns" - it will move the layer list to a separate column on the right side, which will make it possible to use both the layers and advanced or full mode even on the devices with less screen estate