I've been coding for -- holy crap I just did the math -- 46 years. I've been around computers almost my entire life, and like anyone with a similar background, I have a very deep understanding of what goes on behind the scenes and a strong intuition of how to use unfamiliar interfaces.
My wife, on the other hand, uses computers only because she has to. Whenever she has a problem, I always coach her through the solution if I can. I only take over if the solution is so arcane that she will never need to remember it (e.g. driver configurations). Coaching her reinforces her memory of the solution, and I also explain why she is doing each step if I can.
It's really basic learning theory: Providing background information on the problem and solution will help them understand. Allowing them to perform the task instead of just watching someone else reinforces learning as well. For bonus points, they also feel much more in control of the situation and they won't feel "talked down to" (at least not as much, or as often).