Hi Calvin,
There's a list here of customisable Default notifications which can be used in Seminar sessions (I assume thats what you mean).
https://help.totaralearning.com/display/TL110/Seminar+notification+templates
Theres some info about waitlisting here you may find useful:
https://help.totaralearning.com/display/TL110/Wait+lists
Let me know how you get on.
cheers,
George