The so called Transcript Window (See figure 2) is nothing but the main window of AriNET's GUI. It is used to interact with the program and to model arithmetical networks. This is done either by typing code in the text area (see text-area on figure 2), or by using the menu bar.12
To execute a command using the Transcript Window just type it and press the return key. Let us give you a trivial example: let's say you want to add 10 to 987, then you just have to write the following in the Transcript Window:
(+ 10 987)
by pressing the return key AriNET starts evaluating your command and gives back the result on the next line.
The Transcript Window should be taken as an interaction window. As you are only allowed to write one line at once, it is not the place you should use to define arithmetical networks.
This is why the Editor Window exists: