I want to make on the card were ads for just one category, real estate
Please tell me what files are responsible for this, and what am I looking for?

@san4747
Did not fully understand what you want to do...

I want the map to display only ads from category real estate, houses apartments
Other categories to ban the placement of ads on the map

Where to start, how to implement it please

@san4747
Go to file:
oc-content/plugins/radius_search/listings_map.php

Here is everything regarding map and items on it.
Try this following.

Find line:
$radiusSearch = new Search();
Bellow this line add code:
$radiusSearch->addCategory( 4 );
Replace 4 with ID of category you want.
Not sure if it will works, but you got basic idea

So did not help, the card does not work, are there any other options, or where you can read about it?
That only one category is displayed

@san37
Best is to check:
http://www.w3schools.com/php/php_intro.asp

Or directly their documentation.