Required To Choose Background

I am doing a prepay gallery where I will need the parent to choose a background with their purchase.  What is the best way to do this?

In the price list assigned to the gallery -> Additional Order Fields / Options -> Created Option -> Graphics / Photo type.

One additional thing, I added a $2 charge to some of the backgrounds and when we select them, it is not adding that on the price of the packages.

You will need to create a graphic option for each of the packages for the background selection instead of the option in the price list.

That will also add the additional fee. The option for a price with the additional Checkout fields shouldn't be there because it will not add a price.

Thanks Tim.  Just to clarify there is still no way for a gallery to display the png subject preview on a background and charge an upcharge for that background?  

It looks to me with this feature it is one or the other.  No display of subject on background - can charge an upgrade or display of subject on background and no upgrade fee can be charged. 

That is correct. No option to charge a price for a background when using the greenscreen option.