Hi There,
They need to state the following...
Your full name
Start and finish dates
Position held
Brief job description
Part/full time.
Note that your case officer will also want there contact details (name, phone number, email address) and they will most probably be contacted with a questionnaire via email and a confirmation phone call (although this is not always the case).
Also try and include any pay slips you may have or if you're claiming for any work experience here in NZ get your IRD slips (summary of earnings) at the ready.
Good luck