You can share your entire screen with Library staff, or just share individual windows. Library staff can also share with you.
While sharing, you will both have on-screen annotation tools, which let you highlight and make notes on the screen (like a SMART Board).
During screen sharing, whether its your screen or the other user's, you can request or give up keyboard & mouse control. For example, if you are sharing your own screen, this would allow the other user to interact with it.