I would appreciate advice how to "unscrew the screen from the dishwasher floor" of my 2013 Whirlpool Dishwasher - basic model - part of the installed package of appliances. Thank you.

Advice from the AARP Newsletter
Even if your plates and utensils look spotless, your dishwasher may be dirty. Researchers have found that dishwashers often contained bacteria that were linked to health problems, ranging from food poisoning to skin infections.

To clean out trapped food particles, unscrew the screen from the dishwasher floor and remove the filter; use dish detergent and a brush to scrub the filter, then let it air-dry. Oliver suggests cleaning the dishwasher filter every week.