To create a node, do as follows:
Create a note (Method 1):
-click any empty area in the Node Editor to access the work area marking menu and select Create Node. Alternatively, you can select Window > Create Node to open the Create Node window.
Create a node (Method 2):
Select Window > Material/Texture Baking Editors > Hypershade to open the Hypershade.
From the Create bar in the Hypershade, middle-drag a node into the Node Editor, and drop it in the desired location. Alternatively, you can click the node that you want and it appears in the Node Editor.