Creating forms in flash

I’m trying to create an order form of sorts. I am a photographer and I would like to have my clients fill out an online form and have it email to me. I know the basics of creating a form and I think I can do most of it. I would like to have a drop down list of all of the different sizes of prints we offer, when a client selects one say and 8 x 10 it will fill in a predefined price for that size. The other item I dont know how to do is create a total. When they fill in all of the sizes I would like to have an update button that totals all of the rows together. I would also like to have a button to add another row of drop downs. So it would start with 5 rows of drops downs for different picture sizes then when they click “Add Row” it will give them another dropdown to add to the list. I hope all of these questions make sense. If someone could point me to some tutorials or something to help out that would be great. Thanks in advance for the help.

Josh