Entering Greek language is easy:

The menu bar contains two font selectors. The first is the font of the questions, the second for the font of the answers.

Change the first font selector to 'Greek'.

Everywhere in Teach2000 the question will be displayed in Greek symbols.

To know which key to use for which symbol, select from the menu [View][Ancient Greek keyboard].

Better, but more complicated is to use unicode for entering Greek language. For unicode see Unicode.