Nodes are added in two ways to the node editor window:
- By clicking the Add menu in the node editor toolbar and picking the type of node you want, or
- By having your cursor in the node editor window and pressing Space and picking a node from the popup Add menu.
In general, try to arrange your nodes within the window such that the image flows from left to right, top to bottom. Move a node by clicking on a benign area and dragging it around. The node can be clicked almost anywhere and dragged about; connections will reshape as a bezier curve as best as possible.
In this case, a copy of each output is routed along a thread. However, only a single thread can be linked to an input socket.
To break a link between sockets LMB -click in an empty areas near the thread you want to disconnect and drag: you will see a little cutter icon appearing at your mouse pointer. Move it over the thread itself, and release the LMB .
Duplicating a node
Click on the desidered node, press ⇧ ShiftD and move the mouse away to see the duplicate of the selected node appeaing under the mouse pointer.
When you duplicate a node, the new node will be positioned exactly on top of the node that was duplicated. If you leave it there (and it's quite easy to do so), you can not easily tell that there are two nodes there! When in doubt, grab a node and move it slightly to see if something's lurking underneath.