So, we'll start with the differences between black magick and dark magick. First of all, let's get one thing straight right now. Darkness and Evil are two completely different things. As I'm sure most of you have already figured out, you can wear black clothes and have piercings and tattoos without feeling some strange urge to go sacrifice a baby.
Black magick includes things like summoning demons to possess someone. Let's not do this. I can't say I have experience in this arena, but something just tells me it's probably a bad idea. Cursing and hexing, if used incorrectly, can also be considered "black magick." An example of the incorrect use of cursing would be if someone at school gets on your nerves for being a shallow Barbie ho, so you go home and make a voodoo doll of her. Did she really do anything to hurt you? Is she just a poor ignorant soul who is not inherently evil? Leave her alone. That doesn't call for cursing.
Dark magick is a celebration of all things hidden and mysterious. It's actually very psychological, as darkness represents the power of the subconsicous mind. Our dreams, intuitions, emotions, and psychic abilities are all considered to be "dark" traits. This is where the idea of "psychic vampires" comes from... the concept of a person who feeds off psychic or spiritual energy.
I would like to give a quick and easy example of a dark spell. This has almost no materials (one candle, and it's optional) and takes about five minutes. (At this point, I'm trying to keep things quick and interesting. I will go more in depth on the topic later)
Sit comfortably in a dark room
Light that optional candle...if you want (color, scent, size of your choice, yes it can be already used)
Breathe deeply for about a minute, just to chill and quiet your mind (music is ok though)
Close your eyes half way and observe the light of your candle and/or the shadows around the room. Let your vision go in and out of focus.
Close your eyes and see (in your mind) the shadows drawing close to you. They grow taller and take on a vaguely human form. You see they are holding silver weapons, glinting in the candlelight... and shadow. They are strong warriors of darkness. They kneel down before you and present you with their weapons. You take each one and equip it to your person. Next, they offer to shake your hand. Each time you touch one, its strength drains from its hand into yours, causing you to grow stronger, and causing the warrior to melt back into a simple shadow. They have gone, and left you with their psychic strength and weapons.
Congratulations, you now draw power from the shadows!