I would suggest you start with something practical, useful, and easy to learn. It should be something that runs on multiple platforms, and has a rich and easy to use--and free--IDE (Integrated Development Environment, an application used to write, build, debug, test, and deploy your code), and will help remove some of the learning curve for learning additional languages. The only one that really fits that bill is Java.
I agree with what others have said. At 13 with no programming experience, do not start with C or C++. There are many a college freshman who even when knowing several languages will struggle when first learning C and C++.
Java's syntax is very similar to C and C++, they are probably about 85% similar, but Java has removed a lot of the syntax that confuses novice developers and causes many errors. And after you learn Java well, learning C++ or C# will be easier and learning C will be mostly easier. If you decide you like coding and want to make a career out of it, you will inevitably have to learn C++ or C. Furthermore, Java will expose you to object oriented programming, something that is very important if you decide to major in Computer Science in college and/or get a job as a software developer. The other reason why I suggest learning Java is that it is used everywhere. Pretty much every major Silicon Valley web company uses Java for some or all of their backend server code (Google, LinkedIn, Facebook, and Twitter just to name a few).
I would not recommend starting with a scripting language like JavaScript (Java and JavaScript are not same thing at all) or Python. The reason for this is that as a novice coder you will make a lot of mistakes. There are no two ways around that. That is part of the learning process. And you do not want to debug both syntactical and logic errors while learning a language and learning how to program all at the same time. A scripting language like JavaScript and to a lesser degree Python will do just that throw everything at you at once. It is better to start with a language that has more structure and will help you debug common novice mistakes. After you learn Java fairly well, then tackle JavaScript. It has syntax similar to Java, but is a vastly different language. After you know both Java and JavaScript well, you will basically have the core skills to do most software development jobs.
If you want a tutorial to learn Java, I would suggest starting with Marty Hall’s Java tutorial. He is the author of one of the more famous Java books, Core Servlets. And he has a bunch of free Java, JavaScript, and Web technology tutorials on his web site:
http://courses.coreservlets.com/Course-Materials/java.html
Before you begin, download one of the free IDEs to help with written code. I suggest either NetBeans or Eclipse. I think Netbeans in easier to use, plus it comes with support for other languages besides Java (C++/C, PHP, JavaScript, and HTML5) as part of the default installation.
https://netbeans.org/downloads/