Basically, the way it works is pretty simple. You have your Biden safe states, your Orange safe states, and your Battleground states. If Biden loses a safe state, you can stop watching and start the coping process early with whatever your drug of choice happens to be. If 45 loses one of his safe states, then the landslide is on and you can start the celebration forthwith. But chance are, Biden and Orange will each win all their safe states--then the race will come down to the battlegrounds.
If the election does come down to the swing states, then as each such state is called you'll need to enter the number of electoral votes for that state in the corresponding box at the bottom. Keep a running total of the EVs you enter into each box. If the Biden/Harris total equals or exceeds 43, then give a shout of joy because Orange is done. But if they never get to 43, and the Orange tallies up 145 while you're waiting, then it's the absolute worst again.