Welcome to SoM. :)
If you haven't already, scroll down and look in the bottom left hand side of this page and you'll find a list of things: Tips, FAQs and Newbie Central. I would recommend reading through all of these things to get you started.
Before jumping into spell casting, I would also suggest that you learn how spell casting works and how it functions. You can find many informative articles in the article sections, as well as the forums. Use the search bar.
Best of luck. :)