Kernighan & Ritchie (the SECOND edition, anyway) is a good book to learn the basics of Standard C. It does not cover changes introduced in 1999 or in 2011 (the "C99" and "C11" revisions), but the core language hasn't changed much, and some important compiler providers (Microsoft, most notably) have ignored those standards so far.
If your school offers AP Computer Science, take that in your senior year. If so, you'll learn Java in that class so I suggest you use your time with another language...otherwise you'll be bored rigid next year. Good choices include Python (for just about anything) and C# (for applications and games on Windows primarily or on other OSes using the Mono platform).
Each of those (Java, Python, C#) has a large standard library with lots of useful packages for graphical user interfaces (GUIs), networking, file management, and more. The libraries that are standard with C and C++ are much more limited. You need add-on libraries and/or extensive use of specific operating system calls to run in a GUI window, open a network connection or list the files in a directory.
C is an excellent language for systems software (operating systems, device drivers, embedded systems, etc.) but not so hot on its own for applications.
The suggestions for ASP/ASP.NET only work for web apps. If you want to do web programming, learn JavaScript first. There are a bunch of choices for server side web app programming, including Python (with Django), C# (with ASP.NET) and Java (with Java EE web servers). The client (browser) side is ALWAYS written in JavaScript.