Epcar, whether you meant black magic in terms of causing some sort of misfortune, or as a general term for magic, one answer remains the same: there are no beginner spells. But spells can be simple. Do a bit of reading, seeing what sorts of ideas people have used. Be creative! If you use ingredients, candles, props, etc., use the knes which align with your particular tradition and with your desired outcome.
Writing a spell can also be more or less simple; just be careful with your statement(s) of intent, and thoroughly plan everything. Again, using the tradition you study as a guide is very important.