How do I add Groups/Categories and edit them?

In the admin area it doesn't seem possible to add Group or edit them.

I would like to Have my videos organized in 3 tiers:

Group
SubGroup
Channel

Here's an example:

Funny
Commedians
George Carlin Videos

Can this be done?

Or even 2- tiered:

Commedians
George Carlin Videos

Can you give me instructions on how to do this?