For JUnit we need some tools to run this application / JUnit jar
1.) Go to JUnit site (www.Junit.org)
2.) Click on Downloads for the *.jar >> https://github.com/KentBeck/junit/downloads
3.) Kent Beck is the original creator of JUnit :)
4.) Select the latest one as per requirement, if you are not aware which one to use, use the Basic.jar
5.) Jar is a build bundle of pre-compiled Java code.
6.) Download eclipse IDE and this will help us to use JUnit jar in later run.
Soon going to add the screen-shots steps for above basic requirements steps.
Till that time try to go through JUnit site documentation just for information.
Don't worry of things as we all are in the same boat, happy learning and sharing :)