Navigate to the Library via the Page Navigation Menus on the left, and select Files/Folders to open op up the drop down menu and select the type of Files/Folders you want to update.
Now select a Company from the drop down in the top left hand side of the screen. Once you've selected a Company you will see a list of Files associated with that Company.
Find the File you want to edit and select it, once selected a popup window will appear. Here you will see all the details and files relating to this File. Once you've edited/updated the Files details, hit the UPDATE button in the bottom left hand corner of the popup window.