Making a spell can be as simple or as complex as you want it to be. After all, it is really just a way of directing your intent and energy to effect something. When you know what you want to do, find a way to focus your energy and visualize what you wish to be done happening. Using tools and herbs that help to symbolize those desires can increase the effectiveness of your spell.
For a simple one you could just use a candle and some oil. Pick a candle which has a color corresponding to your intentions. Rub the candle with a little oil. If trying to draw something to you like luck, you rub it with both hands in a clockwise motion from the ends in to the center (one hand on each end). If you wish to push something away from you such as an addiction, rub the candle from the center outward with both hands in a counterclockwise motion. While doing this, visualize the outcome of your spell happening. Burn the candle in a safe spot where it wont start a fire. I personally meditate on my goal while watching the candle burn.
It helps if you know your basics as well. You would not want to do a spell to draw something towards you during a waning moon, or push something away during a waxing moon lol.