I'd like to expand on this a bit to make it understandable to a 5 year-old who's never played an RTS or FPS before, and take some inspiration from classic Ren in terms of the first 3 steps. Here's a full start-to-finish script, that i think would be nearly ideal.
The above doesn't really explain the following though, and may want to get worked on a bit:
1) EMP Grenades
2) Smoke Grenades
3) Air strikes
4) Repair tool
5) How to use certain characters for certain tasks
6) The arsenal of neither side is really explored at all in-depth.
7) Crates other than spy crates
I leave strategy out of this in general, because honestly most of that can just be learned in-game. As long as they know not to leave their vehicles out in the open, what a rush is, and general mechanics they should be fine. That's the kind of stuff you'd generally expect to either read up on or learn through playing the game.