Many aspects of the MPW environment are controlled by the document called "UserStartup", which is in the Macaulay folder. The adventurous user may wish to experiment with modifications of this file. In particular the "environment variable" MacaulayPath controls which folders are searched to find commands and scripts for Macaulay, and the "DirectoryMenu" command controls which folders are listed under the directory menu.
For example, if you create a new work folder named "Fun" inside the "Macaulay" folder for some particular project, you might want to add its name to the list of names in these lines of the UserStartup file. Thus you might change the lines
DirectoryMenu "{mpw}" "{mpw}Scripts" "{mpw}Work"
Set MacaulayPath ":,{mpw}Scripts:"
to
DirectoryMenu "{mpw}" "{mpw}Scripts" ^
"{mpw}Work" "{mpw}Fun"
Set MacaulayPath ":,{mpw}Scripts:,{mpw}Fun:"
Note that the useful abbreviation mpw stands here for the full name of whatever folder contains the MPW application - in our case the Macaulay folder. Also, the character which is made by pressing option-d, tells MPW to ignore the carriage return immediately following it, so that the files listed above after DirectoryMenu appear to MPW to be on a single line.
Neither of these changes is actually necessary. The change in the first line simply adds the convenience of being able to switch directories to the "Fun" folder instantly from the Directory menu. (Else you can switch to it using the "set directory" command from the Directory menu.) The second change enables Macaulay to find scripts that you store inside the Fun folder even when this folder is not the current folder. (When the Fun folder is the current folder, Macaulay can find them because of the initial item ":" in the MacaulayPath.)