Empty Tasks without Class and Requirements, how to solve?

I've come across an empty task several times now. How do I get it to display properly? The first time I had this, I just created a class by hand, put in main method and my code, but when I want to hand it in or run the code it just becomes grey and nothing happens. What do I do? System: MacBook Air (2017) with Catalina v10.15 Browser: Google Chrome