Okay, you prolly got the program, not the source code. The program should be 707k. If this is not the file size, delete what you have and get the near infinty program from the NI site.
The link to get NI
Now, to get the java stuff you need go to the link below:
Click get it now (it in the upper right hand corner and yellow). Run through the java set up instructions, install java. Then just run NI by double clicking on it. Then you will need to find the key file for the game, this will be in the folder for the game. Usually
c:/program files/black isle/IWD2/
Hope this helps.