I'm afraid your hopes will be short lived in hoping to find a teacher, learning magic is not about being taught. Especially through the internet! Sure learning from someone in person is quite possibly the best way to learn, but no one can show you how magic works or what it really is simply by typing words onto a screen, it simply doesn't work like that.
However you can teach yourself, and over time come to learn in your own unique way your own abilities and your own style of spell work. I strongly suggest looking up on the forums on this site, many people have dedicated hours to making informative posts which clearly document and reference information that will be useful to you.
Check out these links;
These links will be a good start for you, please do not attempt at this point to try and practice magic, you need a good understanding of the theory first and a strong grasp of the basics which are;
Grounding & Centering
Raising & Sending magic energy
And understanding of magic and spells
Also look into the various systems and traditions, being a witch doesn't mean that you necessarily practice magic, and just because you practice magic doesn't make you a witch. There are many things that people get wrong when starting out, which largely comes from Hollywood movies you see and the perpetual bombardment of the media.
Do not fall into such false notions, instead learn about what the craft really is, whether or not you are Wiccan, Pagan, Shaman, Solitary, or none of them and follow and eletic style. Have a good read through things, and always always keep maintaining the basics for without those your spell work will be utterly useless.
Try to take it nice and slow, magic is a little bit like cooking. Take it nice and slow, ad a dash of love and patience and in a years time you will be so much further than you are now. I understand the need to want to "get there", but enjoy the journey, you are only 13 years old. You have another few decades to progress and enjoy yourself with it!
I wish you the very best of luck and welcome to Spells of Magic!