NearInfinity.jar

Ive spent an hour trying to get NearInfinity to open up ...no luck. I "unzipped" the file into my BG2:EE file and I have the latest version of Java installed on the comp. Ive left clicked on NI - Ive right clicked it and chose Open - nothing happens at all. I vaguely remember something about the "chitin.file" and NI but not sure what it was.
What am I missing here?