Workshop Selector: in C#

3 list boxes, 4 buttons, 2 labels.
The application allows the user to select a workshop from lstWorkshop, Then select a location from lstLocation. Next btnAdd takes the selected workshop and location attached to a set amount of days and a registration fee and multiplies the days by a Lodging fee and outputs this number in dollar form. After multiple workshops/locations have been added btnCalc adds each of these and places them in lblTotal. The other two buttons are exit and clear which have already understand (of course the "easy" stuff)