Hello,
if I understand correctly, you need an online website by the mean of which you control a digital whiteboard whose content is shared with students in real-time and a built-in audio for communications. Right? I think it can be done with a bit of JavaScript and HTML but first, I need some other information:
1)Do you need the stuff you draw on the board to be permanent or should it be deleted at the end of each and every session?
2)Do you already own the server on which the website will be hosted?
Cheers.