Problem Adding New Layer

I know this is a noob problem. But, I cannot figure out how to add a new layer. All the videos on sketchup and youtube do not have the same version of sketchup as I do. I do not have a Layers window like this;
I only have this; “Layer0 drop down menu”

I have the 1st and 2nd floor labeled as components. That is as far I have gotten. Please help. I need to get the house in to layout to draw up floor plans, but it seems I cannot do that without having the different layers. Thank you.

Just click the add button on top left to add a new layer.

Sorry Guy, I don’t see an “add” button. I only have this;

The main ‘Layer Manager’ window is docked into a Tray [that has the ± button etc].
Open the menu item: Window > Default Tray, if it’s not there add it using the pop-out tick-menu, or use the item below that or from the Tray’s right-click context-menu > ‘Manage Trays…’

Finally! TIG, thank you so much! In Manage Layers, I clicked on the default layer, and added a check for Layers. Solved.