In the destination tree pane, expand the tree and select the node you want to map to. A blue area appears on the mapping pane. The functions you choose will appear here.
Click the drop-down menu that contains the function.
Click the function.
A function box appears in the mapping pane.
Map any arguments into the appropriate connector on the left side of the function box. The source can be a node in the source tree pane or the output from another function box. If an argument is optional, then a question mark appears after the argument name.
Map the result from the right side of the function box. The destination can be a node in the destination tree pane or the input into another function box.