It should look like this:

Chapter 1

1.1

1.1.1

1.1.2

1.2

Chapter 2

2.1

2.2

2.2.1

2.2.2

To do this, you need to use the 'Tab' and 'Shift+Tab' combos.

When you start a numbered list it goes:
1
2
3
etc.

When you go to a new line and press the 'Tab' key it goes to the next layer (it indents the row and adds .1):
1

1.1

Press the 'Tab' key again and it goes to the next level:

1

1.1

1.1.1

'Shift+ Tab' makes it go back one level:

1

1.1

1.1.1

1.2

Hope that helps, asdfchanta!