Start Menu -> Control Panel -> System -> Advenced Settings -> TAB: Special -> Enviroment Variables...
Once you got here you can add SYSTEM variables(that's important user with user variables it would not work). Add/edit the following entrys:
Add:
name: JAVA_HOME
value: C:\Program Files\Java\jdk1.6.0_XX(Where XX is the actual version of your JDK)
Edit:
name: path
add value: %JAVA_HOME%\bin; (to the start of the path)
Use Better L2universe server pack cuz this one is so bugged like omG!!!
Veiksmi ar serveri xD