How to use Filters?

[ViVi]

I use slider skin.

I found :
Agenda
Tasks
Exams
General
Countdown
as default filters on todayplus screen.

What do Exams and General mean?

And in Config,there is a page to customize filters.
But in the Name input space.I can't type in it.
So I set up filters of my calendar as
All,30
and Business,30

But I don't know how to choose filters I created on TodayPlus screen.How can I do?
Thanks ..