how to add json jar lib to java using environment variable
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i have prepared a java file that uses Json library so i downloaded a JSON library from "http://code.google.com/p/json-simple/downloads/detail?name=json_simple-1.1-all.zip&can=2&q="
but very confuse where to place it, so that my java file can detect Json library. 

I tried to place the lib "json_simple-1.1" inside "C:\Program Files\Java\jdk1.6.0_07\lib"
but not working yet.

How can i solve the problem using environment variable or any other means where i don't need to set path on comman prompt? 