To get started, download
MEKA and run
run.bat on Windows) to launch the GUI.
The MEKA tutorial (pdf) has numerous examples on how to run and extend MEKA.
There are some examples on how to use Meka in your Java code.
MEKA originated from implementations of work from various publications (note also the references therein). There are some tutorials/slides about multi-label and multi-target classification in general.
Have a specific problem or query? Post to MEKA's Mailing List (please avoid contacting developers directly for MEKA-related help).