Title 1, Title 2 number with sub-numbers in pages

I'm using Pages to write a document.

I would like titles like :

1 Summary
1.1 Start
1.2 End

But I only get

1 Summary
2 Start
3 End

How can I number my titles with 1.1 and so on?

On Pages 13, under Bullet & Lists, just tick Tiered Numbers

on Pages 09 it's in the inspector. Select also Tiered Numbers

The important piece is to set the style of the subheadings to be Heading 2 when the main header is Heading 1

The number of numbers in the title will then be the heading number

For the set of styles see Matthieu Riegler's answer

From my testing, the following applies:

1. Naturally numbering only works when you select Numbered or Harvard from [Bullets and Lists]
2. Not so intuitively, if you want the the tiered number 1, 1.1, 1.1.1 etc. to work, you need to do two things: check the checkbox [Tiered numbers], and use one or more indents to change from 1. to 1.1 or 1.1.1 etc.
3. Styles have nothing to do with this. I have experimented with using and not using styles. It makes no difference. In fact, if you apply tiered numbers to the style [Body] you can number your paragraphs rather neatly.
4. However, I don't seem to be able to include this numbering within a style definition.

BTW, wouldn't it be great if, in the next version of pages, you could see the structure of your document using hierarchical styles ?