How to make a copy of the default theme

Is there anyone who can explain step by step how to make a copy of the default theme so that I can modify it a bit.
I am a user and not a programmer.

The manual states that this is now done via the extension folder. [extension\mytheme\catalog\view\template]
I can create this manually but what steps are needed to activate it?

Cheers

Thanks for the reply, but how exactly does this override work?
Where to place this code and how to activate?

Im struggling with this too!! Can't get my head around how the vents system works. The documentation out there is pretty limited especially when it comes to themes!.

I get how to create the install/uninstall parts in my controller (even though i'm not quite sure how to use them yet!), and I have created a copy of the default theme and called it basic_extended.

I have created a zip and installed it through the installer and realised it removed the 'templates' folder from my upload. After reading many forum post I understand now that I have to create an event to overide the loading of template files, but this is where i'm really struggling.

I have seen the codes below posted, but not with much of an explanation of how to use it/where to put it.

A decent explanation/example would be greatly appeciated if anyone can help?!