Fine question.
I set up a battle (eg. Grand Champ). That is, I choose Play by email, select a scenario, or map and/or army lists and hit Create PBEM Game, deploy my troops, give them orders. I hit the 'P' for 'continuation' and the end of turn splash screen comes up with the diagram of the process. You click on the 'End of Turn' hyperlink and the process In-game is done. Next you go to the SAVE/PBEM folder and the file will be there listed by name and date/time of creation. You can rename it if you like.
So you send the file to Opponent B. They choose move the file into their PBEM folder (note the tip in my first post above) then open Les Grogs and select Play by email then Resume a PBEM Game. They choose the game from the contents of the folder. Game opens up. They do the deploying and orders and eventually hit P. SEnd the file back.
Initially, Player A does not get a view. The computer is generating the movie and all player A does this time is hit the 'end of turn' hyperlink and sends the file back to B. Player B does get a movie of the first 15 minutes of the battle. They hit A which rejigs the game from view into plotting mode. B gives any or no orders they choose, hits P and the 'end of turn' link and sends the file back to A, who follows suit, and so on and so on.
EAch player gets to see the same sequence of 15 minutes each time they process the next file, turn by turn. It's not the same flow as a 'live' battle, but you get to process the turns whenever you have the time amidst whatever real world events are happening.
To get through a turn quicker, either set the timer to run at 6 seconds = a game minute OR use 'T' to move forward in 1 minute jumps (and 'R' to jump backwards minute by minute). This is the best way to rip through a boring marching turn quickly, or to quickly find the point where you want to sweep down in F3 to view a charge or wotnot
Hope that makes sense..