how do you make it so text is displayed in the game when you enter a region and how do you make it so you win the battle when you enter a region

is there a way to make it so you have no reinforcements and only the ones that spawn at the beginning?

and timers in the game, how do you get those to work?

Text: ShowMessageText( <localized text value>, <optional field: team #>)
Winning: MissionVictory( <teams> )
Reinforcements: Yes, just set the amount of reinforcements to the amount of units you want spawned. SetReinforcementCount( <team>, <new count> )

To detect when someone enters a region, read the scripting documentation and learn about events. One of the documents talks about timers too.

Text: ShowMessageText( <localized text value>, <optional field: team #>) whats the localized value?