You can enter a text to any substitution in the field "Substitution text".

If you want to display different texts for teachers and students then use in the teachers' list the column "Substitution text" and in the students' list the column "Subst-Text-2".
Hint: Column width of the substitution text
You can define the width of the column in the printout and you can apply automatic word wrapping with longer texts (see chapter Bold, column width, headings ).
Hint: Substitution text and scheduling dialogue
If you enter a text in the details window of the scheduling dialogue, then this text will appear in the column "Substitution text".