Turn based, table top like strategy war game help

So I've a mind to work on a turn based, table-top like war game, similar to victory at sea, battle fleet gothic, and other naval/space games. I've been trying to break down scenes/screens into a tiered task kind of format to break down what I need into simpler and simpler tasks if it's not obvious how to do based on the description.

I'll share what I have below, but I'm wondering, what tutorials or advice might help me break down and learn the pieces I need to cobble this together?

Start Screen -Background image --Some png or jpeg or whatnot in a frame? -Buttons --New game/ options/ quit? -Music?

Pre-Game Screen -Select scenario -Choose Points Limit Per Player -Choose Number of Players --drop down menu -Choose Number of Teams --drop down menu? or maybe chosen by scenario -Assign Players to Teams -Decide roles for each team per the scenario, “attacker” “defender” etc -Allow players to select units up to point limit --Pull units from a database? Store all unit info in this node/scene?

Game Screen -Generate terrain for the scenario if required -Generate random terrain to fill other zones -Place units required by the scenario

-Game Loop
	--Allow players/teams to take turns placing units within deployment zones according to scenario
	--Begin the Game
		---Turn Sequence
			----Determine initiative
			----Movement Phase
			----Attack Phase
			----End Phase

Post-Game Screen -Show results and statistics for game -Button to return to some menu (pre-game screen?new game? Main menu?) -Button to exit game