JUnit.org Resources for Test Driven Development

Hi,
I am new to JUnit. I just wrote one file in JUnit to test methods in another file. If I put my proyect in a *.jar, when I tried to run it it gave me following error message "....java.io.FileNotFoundException: c:\... ", while it try to know if the file c:\... exists. But if I put my proyect in a folder (without jar extension), I don't have any problem. So I would like to know if my problem is with JUnit or with another thing likes the jar file,...
Can anyone helpme?
Thanks