Well, Riley, it's not as simple as that. There is preparation, much preparation to think of, before you'll know you're first spell. And only you will know what you're first spell will be.
There are many things you'll need to know to start your practice and the best place to start...is at the beginning. Read around, and read a lot. If you don't have immediate access to magick texts, try this site: http://www.sacred-texts.com
You may also want to hone up your meditation and visualization skills and google up some sites about the chakras.