Type 'easy' or 'hard' to begin the quiz. Easy is a 5-degree grid, hard is a 2.5-degree grid. Then, try to name the largest cities in each square IN ORDER. To name a city, you must first click on the grid square to make it have a GREEN border. Then, type in the city answer for that square followed by a '.' (a period).
The squares will start with '0/5' (or maybe fewer cities if less exist in that square). Click on a square and enter the largest city in that square not yet answered (so, the largest city if you have yet to answer a city in that square). You will then have '1/5' and need to click on that square to name the 2nd largest city, and so on until you complete all the cities up to 5 (or less if less exist). If you name an incorrect city in a square it becomes 'locked' and turns red and you can no longer accumulate cities in that square.
You receive 1 point for the largest city in a square, 2 for the 2nd largest, and so on.
AK and HI are NOT included in this quiz.
At the end of the quiz the largest remaining city you haven't named will be shown in each square.
Quiz Takers 
A quick suggestion to quiz takers – on my computer, the relationship between where my cursor is pointed and where Google Maps thinks the cursor is pointed is not perfect, particularly when the red dropped pins overlap. You might have better luck if you zoom in one or two levels when clicking on capitals that are close by each other (particularly in the Northeastern states).
No shade to hugequiz on this – they are doing a great job with the tools available.