help getting started with custom gamemodes

i want to start making custom gamemodes but i really dont know where to even start. can someone help me?

also, are there any commando style strategy military gamemmodes? like sw republic commando or army of 2?

here is a good place to start looking
here is a basic gamemode tutorial
and here is the following version of that basic gamemode( more advanced though )

jeez this stuff is complicated! but im gonna give it my best shot and not submit anything until it is awesomesauce!