Multi-level list

Hi

I'm trying to create a multi-level list. I've used the very helpful guidance from Bob Bringhurst, but I'm not getting the result I want from my list.

Can someone help.

I want to acheive:

Section 1

1.1

1.1.1

1.1.2

1.2

1.2.1

1.2.2

Section 2

2.1

2.1.1

2.1.2

2.2

2.2.1

2.2.2

etc.

Many thanks

Hannah