new workflow definition

Hello Experts,

I need some help regarding workflow:-
The following is the description of the workflow:-

Actors
Accounts Executive (User)
Accounts Manager (User)
Sales Department (Group)
CFO (User)

Scenario
1. Accounts Executive Eners Date for the Invoice and attaches a Document
2. Accounts Manager Reviews the Invoice and Approves the invoice
3. Sales Department reviews the Invoice and Approves it
4. If the Invoice Amount is > 1000000  CFO reviews and approves the invoice
5. Document processing is complete

We will worry about the alternate scenarios later!!.
I have created necessary Users / Groups and associated Users to Groups as
above.

In the sample project:-
2. How do we  associate a State to a Actor (modify processdefinition.xml)
to suit nuxeo EP ?
2. What are the code and  configuration files we need to Edit
(lifecycle-contrib.xml etc) or add.

Thanks in advance for your help. I am eagerly waiting for the workflow
chapter in the nuxeo-book!!.

Thanks in advance for your help.

Thanks and Regards,
Balajee