If you just want a fondant to play around with and learn with, Wilton makes a fondant that can be found a Michael's and even many Walmart stores in the craft section. Be warned though, it tastes awful!!!
A great tasting fondant in my opinion is FondX. It tastes like Marshmallow.
If you want to try making your own there are several recipes on this site. My favorite is the Marshmallow Fondant. Here's the link:
http://forum.cakecentral.com/cake_recipe-1949-Marshmallow-Fondant-MMF.html
I think it's great that you're taking up cake decorating at such a young age!!! 
Best of luck to you, and I hope I was able to help.
I get my fondant at a cake supply store, but you can also get it online. It comes already made. You just need to soften it up a little and you're ready to go.
Wilton is a brand of cake and candy making supplies. Their fondant is also premade, so all you have to do is color it (if you want to) and decorate with it. Here's their link: http://www.wilton.com
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