Thread: "The selection cannot be launched , and there are no recent launches."

I promise to god this is not for a assignment. I want help guiding me for the basics of java. I'm taking java in college right now. And it's my first year. We are reading this book called Big Java Late Objects. We had a assignment for making a "Hello World" program and I finished that & turned it in. Now i'm at home trying to use & understand the program more. My code is below & I cant run the program. I'm wondering what I have done wrong. It says "The selection cannot be launched , and there are no recent launches." I'm using the ide Eclipse because I have to. Someone please explain to me what i'm doing wrong. Thank you for reading.

public class testingprintln1 {
public.static.void main(String[] args)
{
System.out.print("00");
System.out.println(5+4);
}
]