assigning data to lists boxes and combo boxes in userforms

On the excel sheet click the calculate button then click the agree button (even though there is no information you are agreeing to). under the first tab (fluid properties) there is a combo box halfway down the page. i want to be able to select the information available in the tab then click add button then have all the meterials information show up in the list box under the add button. The program is in the attatchment.