If you want to try to make some of these tests pass:
1. git clone git://github.com/kamarcum/java-101.git
1a. If you aren't using git, it may be easier to
svn checkout http://svn.github.com/kamarcum/java-101.git
with your subversion client of choice
2. open eclipse
3. file > import > general > existing projects into workspace > select the directory from step 1
4. find a set of tests that look interesting to you
5. right click on the test file > run as > JUnit Test
6. change the corresponding code file to make those tests pass!