It seems you are unable to compile JUnit Tests using command line.
Please Compile the Java Class, Test case Class and Test Runner class using javac as below.
C:\JUNIT>javac Util.java TestJunit.java TestRunner.java
Now you need to run the Test Runner, which will run the test case written in the Test Case class as below
And finally you will get desired output.
Compile the Java Class, Test case Class and Test Runner class all together with space saperating them using javac.