I think the first thing necessary to learn the game is just to play a bit. You really need to just sit down and have hands-on experience with the basic mechanics of the game. You can go over the fundamentals of position, preflop ranges, and bet sizing superficially, but without first hand experience the concepts just don't make much sense.

If I really wanted to teach someone the fundamentals of poker I would have them sit down with me at the computer and watch me play an entire micro-stakes tournament. I would talk them through my decision making process and explain my rationale for every play I make. When you're not involved in a hand you can interpret the action at the table using it to frame more broadly the important aspects of playing tournament poker.

Make a checklist of the important things you would like to cover and take some time to organize your your thoughts on those topics so you can present them coherently. I would actually write a set of notes for myself, not necessarily to refer to while I'm playing (although that is certainly an option), but just to clarify my thoughts and bring them into focus to make things easier to explain.

I probably wouldn't use a HUD to emphasize the importance of observation, a HUD would most likely just complicate things and be a distraction. Not that you couldn't do so if you felt it beneficial. Using only PFR and VPIP along with a tool like Equilab could be very useful for a discussion of play styles and corresponding preflop ranges.

I wouldn't hesitate to explain things in as much detail as I could, but I would emphasize the most important fundamentals of the game. Tell your student explicitly what parts of your discussion are very important and what parts are more nuanced aspects of the game. I wouldn't expect them to learn a great deal though without playing the game by themselves for a bit.

After that introduction I would sit them down at a computer and let them bumble their way through several tournaments on their own and then I would repeat the process of having them watch me play a tournament, although this time I would cover the same material playing at my regular stakes.

I suspect that the second time around they would be familiar enough with the game to start asking relevant questions and that the concepts no longer being so abstract would sink in more thoroughly than before.

I would also temper my expectations if I were you. Not everyone finds the game engaging enough to feel inspired and motivated to learn the game's intricacies. Not everyone has the personality make-up to enjoy poker and not everyone is self-motivated enough to be a good learner. The truth is, you can only teach as much as a person is willing to learn. If someone is truly interested in learning the game then they will seek out information and all you have to do is point them in the right direction.