Since your title is talking about javac, I assume that you are trying to install Java to compile programs, you can get the latest developer kit from Oracle here .
javac is under jdk ( version ) where. In your case above, since you are on x64 Windows (and assuming that you are using the one I'm connected to), you can install the kit and add the following path:
C:\Program Files\Java\jdk1.7.0_25\bin
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