Email is the best way to ask questions about the course (or contact me in general): email@example.com.
If you ask a question of general interest, I may respond to entire class (I’ll remove your name from any global response). Please do ask questions clarifying the assignments and any other work that comes up.
In addition, feel free to stop by whenever my office door is open, or to make appointments via email for particular times. If my door is closed, knock, and if I don’t answer within a minute or two, I’m probably on a call or doing something with a deadline, so you’ll have to try again later. Note that I sometimes work from home on Wednesdays, though I’m always responsive via email.