first portraits and need help

I will be taking some portraits today of a family of 7(5 kids and 2 adults). They will be outdoors at a park. Do you know of any site where I can find posing examples or do you have any ideas from your own stock. These are not paid just a favor to a friend. Im nervous about my lighting it should be evening sun, but I have nothing other than my enternal flash on my 30d. Can you give me some idea on posing and also general settings for this situation. Your help is much appretiated.