Excel VBA - add functionality to a Form with listboxes

A small Excel/VBA program: Currently existing is an Excel form, which includes some listboxes. Some functionality needs to be added to this form: The form is to fill the first listbox with the contents of some excel cells. Based on the user selecting one of the entries in this first listbox, the form is to fill the second listbox with contents of some cells. This continues for 5-6 listboxes. The contents for the listboxes are supplied in the second sheet of the Excel file, no data import/export needs to be done, only interaction of the form with user and some cells within the file itself. Note: I have the strong interest to continue adding functionality further on in later rounds, with the same programmer continuing on those tasks.