To grill at a public park clean the grates and use foil if needed.
Then build a hot charcoal fire on the grill.
Once the charcoal is hot enough and it's preheated thoroughly, then you can oil the grates of the park grill with tongs and a paper towel.
Then place your meats on the park grill and cook the meats with the direct heat zones and indirect heat zones.
Keep the food rotating and use foil for melted cheese or if you want to keep the grease from dripping foods from falling through the grates.
Also remember to bring charcoal, lighter, tongs and foil and dispose of everything properly, including the charcoal coals once they have cooled down completely.
Also check the park rules before grilling as there may be specific time limits on when you can grill at the park on the public park grills.
And there also can be disposal rules of the charcoals in which you should follow.
Bringing long tongs, grill brush, paper towels and aluminum foil and oil to grill with and clean the grill.
You can also use a grill mat or foil with holes to create a barrier if the public park grill grates are rusty or if you're cooking small food items on the public park grill.
When using a public park grill I always used the direct side and indirect side and after the food is cooked, I move it to the indirect side of the grill.
Direct and indirect grilling creates 2 distinct temperature zones for versatile cooking.
Direct heat (above coals/burners) uses high temperatures for searing steaks, burgers, and veggies quickly.
Indirect heat (away from flames) acts like an oven, using lower, circulating heat for thick cuts, ribs, and roasts.