Yes, you can customise your folders by adding an image such as your company logo. However, the main account folder image can only change by the head librarian. To do this, select the Account tab along the top right of your bookshelf.
Scroll down to Customise Bookshelf Icon - select Change image. Follow the instruction from there. You can also change the colour of the book by selecting a suitable colour from the colour bar. The system will also remember the colour that you previously chose. This is displayed under "your colour section".
Please also tick the "Apply this change to all subfolders" if you would like to apply this change to all other sub-folders.