CMD Won't Compile JAVA FILES

I'v tried everything, i'v tried to create new path in enviornment variables i tried adding this path -->(C:Program FilesJavajdk1.8.0_20bin) to the end of the default path doesnt work i uninstalled and reinstalled and did the same thing over and it didnt work am i editing the files wrong ? what i do is write the hello world program in eclipse to make sure there arent any errors then copy and paste in note pad++ save it as a .java file and it doesnt work i tried save it in regular notepad as .java laso and it doesnt work iv done every thing i could possibly find on youtube is this stuff outdated ? is there a new way? this one one of the errors ill get

C:javat>javac helloworld.java
helloworld.java:1: error: '{' exp
public class helloworld.java {
^

And this is the code for that file im trying to compile

public class helloworld.java {
public static void main (String args[]){
System.out.println("hello world");
}
}