Hi Alan,
If you include a .sub file into your circuit with the .lib or .inc directive, LTspice lets you open the file from within. If you right-click on the directive it will have an option to open it. Try it!
But any external text editor would work, as mentioned before.
As for making subcircuits, keep exploring the "Files" section in the yahoo group, there are lots of help, tutorials, and examples in there.
Especially read in the "Files" section, in the "FAQ" folder, the "Symbols_and_models.txt" entry.
As you have noticed, Yahoo has a "new and improved" user interface for some time to the satisfaction of everyone ;-)
Good luck, Peter