how to refer to a selection from a list or multi-box

[#1]

i am trying to set a variable to a selection in a multibox. I have figured out how to set trigger on selection, but can not find how do i set my variable to the current selection of a particular multi-box or a list. Please help!!!

[#2]

if you want to set a variable to list box or multibox and the variable is product then create a variable vProduct = product

[#3]

thanks!