Install Java Compiler:

Make sure you have the entire developer kit (JDK) installed, and not just the runtime environment (JRE).

http://java.sun.com/javase/downloads/index.jsp

Download the above file and run it.

After you download your compiler, you need to have PATH gone through your compiler folder.

From Search file, you  locate your java.exe file first,
for example, C:\Program Files\Java\jdk1.6.0_23\bin

Right-Click on "My Computer" / Click on Properties.

On the end of Variable value add a semicolon then your folder of java.exe file like
C:\Program Files\Java\jdk1.6.0_23\bin

Click OK

In the first field, enter "classpath"  and the second field enter a single period.

Click OK/OK/OK.