First set-up the game making the newb help. This allows them to get an idea of what is where on the map and what units they’ll have. You’ll be able to throw in some small stuff like IPC values on territories, planes on ACs and what IC’s and AA do. Don’t volunteer too much information not related to specific questions though.
Then you explain the object of the game and how you win.
You then explain the combat move phase and how your actions there help you achieve the object of the game by increasing your income and reducing the opposition’s and that this income allows you to buy reinforcements.
You then explain combat and the various units’ combat values and abilities.
Then non-combat movement and units’ various movement abilities filling in the gaps in combat movement.
At this point you should be able to begin playing. Once started you will have to determine how much hand holding the newb requires in terms of strategy suggestions and being made aware of finer points in the rules and abilities.