When the layers toolbar is closed, you can add new layers by clicking on the + symbol. For all other settings, open the window by clicking on the double chevron.

The layers 

Each layers is shown with a number in the layers toolbar. Click on the layers to adjust the view in the editor. If you click on the small arrow, you open the layers information.

Here you can see all the drawn nodes that are visible on this layers. You can see which node it is by the (1) node number, which also marks the respective node on the drawing area. In the layer toolbar you can (2) show or hide nodes (this view is only saved locally in the editor, is not visible to your team members and does not affect the live map), (3) lock or unlock them to protect them from editing (this function affects the editor view, is saved on the server and is therefore also locked for team members, but does not affect the live map) or (4) delete them.

You can also apply all the functions mentioned above to the entire layers (5) by operating the icons of the layers accordingly. Delete a layer, hide or show all objects of the layer locally and lock all elements of the layer with only one click. 

Note: If you lock a layer, all elements of the layer are locked. These are then locked across all layers on which they are visible. 

When you draw new nodes, the newer ones will always overlap the older ones. If two nodes are visible on a layer and they overlap, you may want to change the order. In this case you can adjust the order of the node in the layer toolbar by dragging and dropping (6). To do this, grab the dotted line at the left edge at the double bar mark and move it in the list.