How to create a campaign?

[Imp]

Hah lots of time & patience, depending on how real you want it check google earth for likely routes, cities airbases etc & plan battles before start it having a good idea where it is going.
Your proposed forces for it to be any good either the player has to be Yugoslavia or if Russian say a Mech formation with tanks or SPATGMs in support.
No MBT the AIs armour will be cannon fodder T-62 should be the best tank available for human use.