Create the list that you want to appear in the drop down box - with each list item in a different cell. Then select a new empty cell and go to the toolbar and select data then validation. You will be presented with a data validation window. From the data validation drop down select list. Then click the 'button' at the end of the source box. Highlight the cells that contain the list you created earlier and click the 'button' again. Then click okay. Your previously blank cell should now have a drop down containing the contents of your listed cells.